ECM usage will depend on:
a)If the engine is going to remain stock then the GM electronics if you can tolerate DBW is less painful.
b) how good you are with wires and computers.
If building a harness and tuning is not a problem for you then MS can work. It does take time and reading to be successful.
I am in the process of getting the sequential megasquirt (MS3) with VVT working - this is a work in process and I do not know yet what the final result will be.
Oil pan - I have a solution.