Heads are getting more and more plentiful for 96+ SOHC motors. Most are cnc ported pi's but trick flow has some really nice heads out now. 6k if all new. Shop around, find used stuff here and there.
call me biased, but i am of the opinion that, dollar for dollar, a 351 based platform is easily the best platform available for our cars. the car you are looking at already has that, and that is a very big selling point for me, especially if your main goal is going as fast as possible (as opposed to the creature comforts you mentioned earlier).
there are lots of guys over on hardcore50 who have 351-based motors and are in the low to mid 10s. of course, they are either stroked to 408+ or boosted. With 351 cubes and NA, you can probably go 11s all day, but you'd have a hard time getting into the 10s.
then again, there is a guy over there (pure street) with a NA 306 who is in the 10s ... killercanary knows him
Yeah definitely not arguing that it would be cheaper to go faster. Which is a plus in its favor. But there would be a little body work that would need done, car has no ac, would need a tranny upgrade. So here is my solution, at least the temp one. Keeping the 2v car, buying a blower with the money I loaned the government last year. However not giving up on the pushrod idea. Found a smoking deal on a black on black 95 Cobra coupe. Should end up with 2 mustangs. It may take me a while to get a car to my goals but I think I like this way best.