L31 engine swap questions

[memo43]

Good day all.

My son and I are in the process of switching out my his tired sbc350 in his 86k20.

Well not really tired but started making a clicking/knocking sound towards the bottom rear/ flex late area. I told him if its the flex late its an easier fix.
If it is internal we are swapping engines.

I fell into a killer deal with a crate engine with 3k miles,
co workers son wrapped an el Camino drifting into a telephone pole. ins company totaled the car, but I got the engine.

The block is an 880 block with I believe to be an L31 Vortec engine
1 piece RMS.
My dilemma is should I run it with the current serp set up (no ac brackets)
or switch his V belts back on and keep his ac