I would call that stuff minor...stuff I can do in a day without tearing the engine down...where can I find more details on the M1 intake manifold/TB?
For the throttle bodies, there's a guy who sells 52mm ported ones (stock is 50 necked down to 48 below the plates) on ebay for $150-ish. For the M1, they're getting a bit tougher to find, as they're now discontinued. Personally, I'm running the Hughes Airgap intake manifold, as I didn't feel like waiting to hunt down an M1.
If your metric is stuff you can do in a day with the motor in the Jeep, heads aren't actually too far off. It's a solid weekend job, no need to pull the motor. By the time you get that far in, you definitely need to start tuning though.