340X heads vs late model LA heads vs Magnum.

Labor is free as I will be doing almost all the work myself. If I use the heads I have either the 318 swirl port heads or my 340x heads the I am out the cost of valve springs and gaskets. More on the 318 heads as I will need larger valves and seats installed.

I plan to update the intake either way.

Does anyone have a way to check valve spring tension with the heads still on the car?

I wasn't talking about the cost in money. It's not free, even if you do it. You spend time and energy doing it. You will have that in it. Knock it out. Let us know what happens.