68 c10 327 with no power

[vettetlb]

Ok guys. I need some help, thoughts, or ideas.
My 68 327 just won't accelerate.
Original 327, edelbrock manifold and carb. HEI distributor. Headers. 700r4 trans. Had the stock cam until just a couple weeks ago. Thought maybe the cam was worn out so put in a 268 cam. Same issue.
Revs great at idle and sounds strong.
Get out on the road and it just wont go. No bog, no missfire. Just lazily inreases speed up. Takes forever to get up to 70 and wont go much past.
Timing at 7 btdc. Mechanical and vacuum advance both work although i don't know my total timing. Vacuum at 18. Fuel pressure at bouncy 6-7 psi.
Thoughts?