I completely agree that even low powered cars can be just as fun as high powered ones. But the main thing for me isn't just the fun, but the freedom to build how I want. I won't exactly be after power immediately after I buy the car. I'm after an older chassis that will likely start as a restoration project that may up snowballing into a more serious project (hence wanting something that I can easily up the power on). There is only one reason for that older chassis. Smog exemption. Let me take this time to explain the stupidity known as California car laws.
The only engine modifications allowed are basically drop-in filters (Not literally, but it may as well be that ridiculous). Any other engine mods require a CARB certification or exemption and a sticker on the part itself, otherwise it's illegal. CARB being the California Air Resources Board. I'd say 95% of manufacturers don't bother with CARB approval. So say you have a car with a highly modified engine and get pulled over. If he asks you to open the hood and he's unsure what is legal/illegal, he can send you to a state referee. State referees know exactly what to look for. He'll mark down anything illegal and tell you those parts must be returned to stock.
That's the risk that you run when you do engine mods in California. But let's pretend we're in a situation where we don't have to worry about cops or state refs. Well, you still have the other major problem. Passing smog testing and registering your car. This is what got me. The only reason I could register my car in California is because I paid the smog technician $300 to "pass" my car. Now, California has cracked down on these "buyable" smog techs, and I lost my hook up. I couldn't get it registered because it wouldn't pass smog. My standalone ECU was mounted on the passenger kickplate, and any smog tech would have laughed his ass off while giving me an automatic smog failure.
True, I could have just as much fun in a car with 200HP as a car with 800HP. However, buying a pre-75 chassis at least allows me the option to build to 800HP. Legally.
Something 70s and European could work. So long as it's pre-75.