Find a used engine. If you overheated it to the point that it blew an oil line and died from oil starvation, it will take waaaaaaaaaaaaaaaaaay more than a "mini-overhaul" and $1500 to get it going. Expect pistons, cylinder sleeves, bearings, probably some valves and an injection pump rebuild too by the sound of it (PLUS core charge if the pump is not rebuildable). Parts cost of the pistons, rings and sleeves alone will easily pass $1500, not counting shipping and installation labor.

I love that you've gotten a 617 into a G (please post some pictures of it!) but you screwed the pooch not stopping at the first sign of problems.