1968 Ford F100 4.9L 300

to make a long story short a cheapo chinese oil pump shattered a rod 3 miles into my rebuilt Ford 300 leaving a half inch long hairline crack on the crankcase, an inch or so above the oil pan gasket. Mag checked looked fine but apparently this turned out not to be true. Rebuilt again and running good, but There is a very slow oil leak from it (ie. top off every 100-200 miles).

Short term: I’ve been dailying it. Any harm continuing to do so, and take on longer drives, without worry, so long as I closely watch oil level? I RTVd the chip to slow the leak and prevent air from getting in.

Long term: this is a very large engine bay and I can access the area with a welder. I am aware proper procedure would be to hot tank before and after but there isn’t a chance in Hell I am taking this engine back out (done one for initial rebuild, again for second rebuild, and had to mate the tranny a third time when the clutch linkage came apart). Can I just clean the area REALLY good, weld, and use a magnetic drain plug and get away with it?

See attached pic, with half inch nuts on the fuel pump for size reference. Hairline crack is inside the chipped paint area.