You might be right on the Cain intake. I am not familiar with those. BUT, it's very similar in design to the Offenhauser, so I would assume similar in performance and function too.....but you know how assumin goes. lol As for valve springs...I imagine the 340 spring would do for most any cam you'd wanna run.....but you got Frank's help and as he said....the head will be RIGHT....so you've got that covered. As far as the 170 and higher rev thing and all.......for a street car, my personal choice has always been the bigger cubes, cause you need torque down low on the street and smaller cubes don't produce there. Anyway, I'm anxious to see what you do as I'm gonna build a slant as well.
