Mercruiser drive is shot any suggestions? donors?

[McGillicuddy]

Took the 21 in for assessment because it was dripping gear lube through the upper housing and am told its gonna need a do-over.

It's an original type 1966 Mercruiser 1-C sterndrive and it served somebody exceptionally well...I knew it was a matter of time but had hoped to run her a few times before having to ante-up.

Should I have it rebuilt (about $1500), or find an Alpha 1 and modernize (about $3K). Any thoughts on the Sterndrive Engineering Inc products or finding a used unit, Seem to be tons of alphas on ebay, cl, etc. for under a grand...

I wasn't expecting this so if anyone has some thought on the best way to go I'm open for suggestions...