I cut my cold start chops on a 911 with a 930 turbo engine that had been hot-rodded. In Rhode Island. It was my daily driver so I spent the time to get it right. Not everyone has the time or inclination to do that, but Carey is right, it's not easy.
Here's my current situation. It's very important to realize that it's where the nighttime lows are in the 60s. Not really cold.
I've got my 1776cc starting in the first 1/2 second after turning the switch and drivable immediately thereafter with no bucking or stalling. The air:fuel mixtures aren't what I usually run, but they're close enough for safe driving. They settle down after a couple of minutes.
This is done by data logging every cold start and figuring out what the engine likes at different temperatures before cranking (priming pulse width table), in the first few seconds after start (afterstart enrichment tables), the engine warmup enrichment curve and tricks for setting idle cells spark advance and using the idle advance tables and idle air control tables to keep the engine happy as it warms up.
There are a lot of moving parts to a good cold start. It can be done, and I wonder if my settings are close enough to help others get a good start (see what I did there) on their engines with different displacement, compression, cam profiles, etc.
I've encouraged Danny not to make any big changes before the upcoming trip to the Smokies. But maybe we'll get another data point after he returns and colder weather starts to set in.
On a final note, around 20 years ago I experimented with several piggyback ECUs that clipped into the stock wiring harness. They essentially added additional injector time at higher engine loads and speeds. I liked them for the simplicity and the fact that all of the factory programming took care of the hard parts. I haven't looked at them since then, but maybe that's a tool that could be useful for the Suby folks who go for more power.