<the boss 302 is the same size obviously... but pushes out 60 more horse power... why is this?>
Dont forget that the boss302 was a engine for a production car- had to meet durability/warranty concerns...you could put a hundred or two extra horses by just adding nitrous, but after a few minutes of use, something in the bottom end might give out. Ford put the best they had into the B302 bottom end so it could both perform well, and last a long time.
the Boss302 was a kinda hybrid engine-probably wouldnt bolt in place of a windsor- valve covers on a windsor are 5" wide, 6" on a cleveland- so you can imagine its a lot wider, and I dunno but doubt exhaust/headers would fit up without work. The 302 Boss used the heaviest 4 bolt main short /mid deck 302 windsor block Ford had, with a variation of the canted valve Cleveland heads. With the high flowing heads, I guess it was quite the screamer in its day...I think it came about as 69 trans-am series races were limited to 5 litres, so Ford and Chevy both built some high revving 302 inchers for racing, that trickled onto the street as Boss302 and Z28 302's. By the way, I think Ford kicked some butt that year didnt they?
You can put cleveland heads on a 302, but thats probably the easy part- I'm not sure if you need costom pistons, or if standards can just be re-notched for the canted valves, custom pushrods or not, etc...heres a place that sells adapters for putting 351C-2V heads on a 302:
Im kinda thinking about trying this out just because I still have a set of early 351C2V heads, and a 302 Edelbrock manifold- and a guy at work offered to give me a 302 shortblock thats supposedly only needs cleaned up...we'll see. The thought of intake manifold spacers sounds like asking for a vacuum leak though. Might be cheap partswise to do this at first glance, but considering its kinda off-the-wall combo, things like custom notched pistons, special length pushrods and such might make it costly or difficult to piece together.
with the aftermarket heads available these days, most guys seem to go that route, personally I kinda like Iron heads, as the headgaskets *might* hold up better if block/heads are same material-same expansion rates...these days gaskets seen to handle this pretty well though.
Regarding the blower, a paxton or vortech will go right under the hood- but think youre looking at 3~4k for a complete kit(just guessing)