The slant or the 318

What are the cam specs? Depending on the specs,you may not have enough compression to make up for the bleedoff,and that clifford is hurting your low end big time unless you are running a serious cam,and high compression.

Really your 65 should be as fast,or faster than your 70 based on mods to both,weight,transmission/gears.All im trying to say is that you may be leaving some power on the table with your slant car.

BTW I love that 65,its a badass car.

280/270 Erson 9.5:1 compression. This build was carefully planned, not just thrown together.Ive been tinkering with these 6's for years.Had everything from a 1 bbl, Super Six's, to 4bbl's. With the 4spd, the car is just fine down low, and gets out of the whole quick.The Clifford isnt killing anything. Like I said, the car runs flawlessly, and is a blast to drive.

Leaving some power on the table ? Perhaps, but you can say that about any car. Maybe a trip down to the Dyno could add a couple more ponies.
But like they say "There is no replacement for displacement".