No top end power, need help

I'd be backin' up a step or two.

Use a piston stop to verify timing marks are accurate.

Do some checks for sloppy timing chain.

Use a delay timing light, "crackedbacks" idea of temporary "timing tape" from masking tape, or just sit down and scribe some degree marks on the balancer, so you KNOW where and what the timing is doing.

Regardless of "what the engine likes" it should run pretty fair "on top end" at 34-36* total timing, no vacuum, until you get this sorted out.

And take the trouble to "map" out what the mechanical advance is up to, IE too slow, sticky, rusted shut, and check the dist. for wear.

THEN after you know what the timing and spark is doing, go after the fuel.