Ayuh,..... Welcome Aboard,....... Now a days, starters are replaced, not rebuilt,.....
Yer probably lookin' at the Chevy, straight-across bolt pattern starter,.....
Find yerself a copy of the new PM starters, a Marine rated one, in the Chevy straight across pattern,....
'bout 1/2 the weight, 'n nearly twice the crankin' Power,...
Just make sure ya get new replacement bolts with that starter, for that starter,.... they're slightly shorter than the bolts for the ole style starters,...
If ya reuse the ole bolts,... you'll "Think" they're tight, but they won't be, 'n the starter can schuck, 'n/ or break the mount,...
Our Chevy based boat motors only basically use 1 of 2 starters,....
The Straight across bolt pattern, 'n the Staggered bolt pattern,....