im trying ti figure out what the diference between a boss 351 and a 351 c and what componants are need to make one such as having to use a 531 windsor or a cleavland to do it.

This should help.
http://www.boss351.org/engine.htm

It has to be a Cleveland design, and not a windsor.

The 351 Cleveland and the Boss 351 are the same engine, Clevelands. The different is the Boss is more of a High performance engine. The Boss 351 uses the Boss 302 heads. They have bigger valves, valve springs and adjustable valve tran. The Boss also has 11:1 compression and uses a 750cfm 4-barrel carb. You could modify 351C four-barrel heads into 351 Boss heads by milling the rocker pedestal down and taping them for adjustable studs and guide plates. Plus the spring pocket diameter will need to be machined larger.

Hope this helps

Tony B.

you can check out this website www.sasnak.net/boss351

marlon
www.fly-ford.com/