Man you got the bug worse than I do! LOL! Nice score!
My V174 originally came with the Mercruiser 120 and also had the 2nd key thing for the tilt but it had been disconnected. The key was to unlock the drive so it could be tilted, the locking mech had been removed by some previous owner and you'd be hard pressed to find the parts. The V174 would get up to 40mph wide open with a stainless 21 prop, should do a little better in the V164. If it comes to it you can always convert it to an Alpha and a 3.0.
I am truly ill.
But I do think I might have a long term plan.
Get the V164 back to original as possible and usable. (seats, remove boarding platform)
Ditto for the V163 (carpet and seats
Finish the 175
Pillage the 305 and out drive out of the SSV and install in the 67 174. Then I'll have a spare 120 for the 164. Besides, there is little to work with on the 174 unfortunately so maybe a Rat Rod style boat. Nothing too crazy besides the V8 transplant. No over the transom exhaust or naked women on the bow.
Stick a 2 K into the 61 and sell it for 1200.00
Viper is in there somewhere. Probably after the major loss I take on the 61
Then I'll have an outboard, an I/O, a jet and a freak.
I better get busy!