In general, the 50 hp J/E engines were very good, but your '72 was only the second year that engine was in production. they built that engine up until 2004.
Any 50 hp OMC motor, 1975 and later will be fine, as OMC had redesigned corrected these shortcomings by then. As evega stated, the hydro-electric shift went over to full mechanical shift back then and now, just about any OMC control will work.
You will find that these motors all look identical to your 72 (except for paint and decals) up to about 1987, when the lower leg and clamp arrangement was redesigned.
I have own several of these engines ( '75, '83, '92 and '99) and they are damn near bullet proof.
Good luck with your 72.