comp 306/ported heads/ etc. Are 42lb injectors overkill? will they work ok for my app?

 

Those are overkill. 30's would work, 36's would be better if you want lots of power in the future.

 

I agree with superjerry in regards to the overkill opinion.

Since those injectors are a solid 30% bigger than what you need, they will be way too rich at low RPM, but you can band aid that through tuning. The best way to go is with the right size injectors from the start.