I had .060 taken off my heads and they cut the intake side but don't know how much. Didn't do anything to the block or intake and didn't have any problems.
Here are so pics of the spindle that I have. I tried to find some casting numbers online to see what side it was but haven’t had any luck with that. Maybe you can match it up to what you have or need. Threads on the spindle are good as are bearing surfaces and all the other bolt hole look good...
https://www.mopar1.us/headcastnumber.html
This shows the heads to be 83-86 police heads with 1.78 intake and 1.60 exhaust valves . I don't know the difference between police heads and other LA heads of those years.piston may have other numbers or markings on the bottom that may help identify them.
I have a 66 Valiant with a 273 original manifolds and similar cam. I have flow master 40s on it with 2 1\2 inch exhaust. At certain rpms the drone .makes it feel lime my head is going to explode. Sound good outside the car. I have some magnaflows to put on hopefully they are better.