Diffinately don't apply the Marine Tex over any old repair, I have repaired exhaust manifolds, cylinder heads, blocks and tractor engine parts for decades using this stuff. Whatever repair needs to be worked, sand with real corse paper, and yes stop drill the ends and V edge works also. Pneumatic air and even a corse file has worked for me without any problems. Make sure the repair is real clean before you apply the M.T..
