Sleeper63
Ok You have to buy cleveland type pistons because of the canted valve heads, thats what makes it a clevor.
They make kits to do just what you want to with the 351W now.
The block has to be threaded to accept bigger head bolts and there are alot of
other little tricks you need to know about.
Back in the 80's we called them Mexican Style Boss's but it's really the same thing.
The only one that made a intake for them back then was Yates racing.
Today there are lots of companies making kits to do the same thing.
You want to talk to Dave Severson on here, He was talking to me awhile back about
a new head that they make now to replace the 2V and the 4V heads.
It take the best things about both the heads and combines them with alot better flow.
Another guy you may want to look up is Rick DeVitto and his 65 Ranchero.
He is not on here but is a friend of mine and is running a 408 Clevor in his Ranchero.
Just type his name and his car in and it will pop up if you Google it.
He will be able to answer most if not all your question about a clevor motor.
Hope this Helps, Kurt