well....through the engine mounting holes, the transom wood "looks" ok.....but the "factory installed" aluminum seems a little thin [to Me]....we would rather have it overkill than have "issues" later on....Besides, I don't see an "easy" way to replace that wood....thus, the added alumynum....
Overkill often puts additional stress on other areas not designed to take the added stress. And gives the impression of a band-aid 'repair'.
No pix, so no idea how easy or hard it'd be to replace transom wood on a Fiaher Marine tinny.
If its got a foreward facing skin on the transom ply already, those types of factory builds typically hide the worst corrosion damage to the aluminum and masks compromised ply transoms......
Although a typical point of water intrusion, motor mount thru holes only give you a <5% 'view' of the transom...
Again, a lot of time and expense to get to this point, short sighted to leave transom.
BTW:
@gm280 Its not his boat, its someone else's, who I'm guessing has no idea about boat rehab work and is dependent on his rebuilder (the OP) to build out a safe/reliable rig. Not quite there, IMO.
Any other 37yr old original plywood show any damage? 1 of the very few to be 37yrs old and not need transom work. Small handful over 1000s of rebuilds. Much younger boats have needed it w no visible evidence of how bad it was until it was pulled, plywood and/or aluminum hull skins.
Good luck w the rest of your project.