Anyone have a dimension of the width and height of a real 356 center tunnel? Thanks!
Jeff
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Bump!
With all the minutiae details to be found on this forum I would think there's SOMEBODY on here that can provide this info for Jeff! 
Peter Venuti in Mass. would know he's been working on a coupe for a while, or maybe Carey Hines.
Jeff, I just sent you a private message with Peter Venuti's contact info. He's working from home so he should be able to go into the shop and measure it for you.
Maybe this will ping his email, too: @PVenuti(356FAN)
Gordon
I found in my notes 135 x 55 mm
Cool. 5.3" x 2.16" thanks!
So you're going to cut the VW tall hoop center tunnel down and replicate the 356 tunnel? Hopefully getting rid of the hand brake there and adding the older VW turn knob for heat.
Check this build out - He did same
My Speedster-The Black Sheila | 356 Speedster South Africa
Yes, exactly that. Not trying to reinvent the wheel or anything. 
A few people have asked why I want to do this. It's mostly about my wife. Her back needs comfortable seating and the stock buckets would never work. I need to go with roadster seats. I have a set of late 356/ early 912 seats I plan to restore that would more than likely work for her. The issue is that putting them in a speedster, they need to be mounted lower and the tunnel gets in the way, not to mention the parking brake would never fit between them. So, chop the tunnel, lower the shifter, relocate the e brake and put in a different heater knob.
Jeff
So... the tunnel is not the main problem with a pan-based replica, Jeff.
The main problem with the vast majority of pan-based speedsters is that the subframe members run inboard of the door openings, creating a really wide sill and a seating area that is significantly narrower than even a VW Beetle.
If you want to run wider seats, this is where I'd concentrate my efforts. There's zero (like no reason at all) why that longitudinal frame member should be where it is. Getting the subframe remade would be the first order of business towards getting a usable seating area.
Remember that in removing the VW hand brake and going to the 356 umbrella style unit- handbrake turns will no longer be in your repertoire of driving techniques. You also won't have any use for one of these that I'll be putting in the raffle pile at the next Carlisle weekend I attend...
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Yeah, the outer sills are an issue. I remember the fiberfab I had and their width.
As for e-brake skids.... no, not in a speedster. I drive like a grandma on red bull; sporty yet very cautious!
That looks well-done, but consider how much strength was removed from the "spine" by lowering it so much.
For me, the body going on it would require far more subframe than Speedsters usually come with. Full tube frame with cage comes to mind, or just go with the real 356 coupe full unibody...
Looks scary to me. The Speedster pan had a lot more bracing. In no way resembled a VW pan. I guess all the kits have a built in perimeter frame. I like the flat tunnel.
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@James550 posted:it has been reinforced by this way
I's bet that is going to drag on just about everything.
Looks like 1 x 3. I could run 1 x 2. It would be good protection to the coolant tubes.
Looks scary to me. The Speedster pan had a lot more bracing. In no way resembled a VW pan. I guess all the kits have a built in perimeter frame. I like the flat tunnel.
Porsche 356 models didn't have a "pan". They were all of unibody construction.
While the referenced drawing is of the main strength structure of the unibody, it could not be unbolted like the VW.
I don't like the idea of the 1x3" steel attached to bottom of the tunnel. Seems it would very easily bottom out on speed bumps and humps! The normal pan perimeter frame is quite substantial except the very corners could twist. Maybe adding a couple cross pieces of 1x3 steel for seats to sit on would help to keep that twisting down. Along with some gussets in corners. A rear roll bar or even one that just catches the shoulder harness would help too.
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1x3 would be a bit tall. I was thinking doubling the tunnel wall thickness on the inside.
The gussets would be a great idea too.
I would lay the 1x3" for the seat supports so they only stuck up the one inch.
Vw originally put in frame/ body stiffeners under the running board mount area on their bug convertibles to compensate for the loss of structural/ torsional strength of a roof.
Lots to consider and think about. I love this stuff!!!!
Jeff
Unibody adds a lot of strength so maybe adding to the inside of the lowered tunnel by welding in a 2inch bar on both sides for the whole length of the tunnel might add to the tunnel stiffness then do the other body stiffening stuff like gussets to add to the overall rigidity would be great but as Stan has said the interior width and foot wells I would address as well