I run Hedmans and they are probably coming off after reading the thread about actual HP difference around 300HP. Part of the reason, though, is that I'm thinking of turbo, and "having them off" will save heartache (to remove) if that happens.
But they do fit. Problems I had may have been due to biscuit mounts in my 67. When I went to a spool mount K frame the "fit" improved in some areas
Problems with the 67 biscuit mount K:
Had to dent the headers on pass side for T bars, and to clear aftermarket pan flange (Miloden)
Had to dent driver side but don't remember why.
"Big" starter clears. You have to remember the jigs for these were first built long before min starters were ever dreamed of
I don't run a 90 adapter. "Short" (51068 Wix) filter
With the spool mounts, it turns out to be nearly impossible to remove the block drain plugs
Not sure how well they fit or not with PS. I have a manual box
Only time I scraped the low tubes was when I mis-judged a poorly marked curb and actually drove out over part of the curb. But you DO have to keep this in mind and not go "off roading" so to speak.
For bolts, I use standard bolts on several on both sides. I think the right side had two header bolts.
On the left, there were two that use small head (header) bolts, and a third, the one next to no5, I used an allen head, which I access with a ball head allen wrench