Like Dan said; one has to measure the engine to be modified in order to decide on what has to be milled and or changed for a given result.
You need to pull the head, and cc its combustion chambers, measure how far down the pistons are at TDC, diameter if bore, and know thickness of head gasket, and stroke. Than plug all the information into an online Engine
Calculator to determine what you are starting with.
Once you know the existing, one can make the necessary and most cost effective modifications to reach your build goal.
If your build is going to be on the radical side, attention to torque converter stall speed, rear end gear ratio, and tire size need to be addressed in order to extract all the performance your build can produce.
Planning is cheep, repeated rebuilding using R&R parts shotgun approach is expensive and unproductive
If you are planning on using tube headers on a 170, and have power steering they may hit on top of the steering gear, and not fit. The top of the 170 block is one inch lower, or closer to the K member than a 225, or 198 block.