Can the timing out by a little make such a dramatic difference in power?

It's running lean on occasion too, what does bagging the engine mean?
How would I know if it happened?

1971 Datsun Fastback Rolling Chassis. Chassis constructed of mild steel with a 97 1/2 wheel base. Custom built and finished by Takash Racecraft in Orlando. Has 9" Ford rear housing with four link suspension. One piece fiberglass nose. Intercooler, removable steering wheel, all aluminums, gauges, three piece wheels and tires. Aluminum seat, brake master cylinder. Needsall brake lines and calipers, third member in rear end and axles. Needs wiring harness, hoses and motor and transmission. Has not been on the track yet as this proyect is not complete. Need to sell due to illness and would consider trades if reserve is not met. This vehicle can be seen in the Orlando Florida area, just email and I will forward further instructions. Has plenty of space to accept any motor, transmission combination including rotary. Other misc parts included.