Larry, we are pushing lighter cars (less rolling resistance) with (in most cases) reduced frontal area and usually more than stock power. Building a Berg 5-speed with a 3.88 ring and pinion and carefully selecting the transmission ratios (there are quite a few custom ratios available) can give a VW engined replica much improved overall performance and a decent cruising speed without any engine heating problems.
Of course any time you want to make significant changes to a car's power delivery one should consider and provide for any anomalies that might arise - like if the cooling fan speed is a bit too low at the desired cruising speed, speed the fan up at that RPM via different sized drive pulleys. Porsche increased fan speeds on their USA cars after they found out most US drivers were puttering around at low RPM in fifth gear on the freeways.