Two good choices of cars, ERA and SPF. I have been trying to arrive at the same conclusions as you. I'll share what I have learned, AND leave myself open for correction, by all means.
Within the budget you've set you will be looking at used vehicles, and I think this is almost without exception for these two makers.
Keep in mind there are a ton of SPF 427 cars running small blocks, typically some variant of a 351Windsor. They are plenty fast, but distinguishable from big blocks, either FE's, Cobra Jets or 385 series, certainly in appearance under the hood, and arguably in sound
although this thread will run to Mars and back if we take up THAT particular discussion.
Simplest advice on the 289 cars the choice is easy, small block 289/302, 351W. On the 427 cars, a big block will fill up the engine compartment if you want that look of the old 427 and 428 big blocks, but there are plenty of beautiful 427 replicas with small blocks. Some folks here feel more strongly about this than others. Choice is yours. The vehicle is for YOU, no one else.
