318 bogging at high rpm, but only in first gear?

I’m pretty new to this, and can’t logic myself an explanation.
1974 318, some cylinder wear, nothing terrible
1971 stock heads with a fresh valve job and springs were tested
New lifters
Double roller timing set
Unknown cam, either stock or very mild, no advance
TDC confirmed, as well as cam timing
Edelbrock performer intake and 1406 carb
Dual exhaust, 8.75 - 3:23 gears
Proform distributor and Accel coil
1977 A904 Torqueflite

First, the engine wants a ton of initial timing. Tuning by ear, with vacuum port plugged, idle keeps rising until 25° or more of advance. I dropped it back to 18°, don’t have a tach or an advanced timing light to check total timing. When I accelerate hard from a stop, it goes fine, (if a little underwhelming), until it gets to higher rpms, then it bogs right out. Doesn’t stall, but zero power, rpms drop. Then once it shifts to second, it’s fine, and doesn’t do it in second or third at high rpms.

So it doesn’t seem to be a fuel issue, since it doesn’t do it in other gears. Ditto for timing. No discernible vacuum leaks.

Any ideas? What am I missing, what should I be looking for, and has anyone else dealt with a similar issue? When I search for it here, I’ve never found a post where it was in first gear.

Thanks!