Here is the one I bought for mine it comes with great instructions and is about a 1/4 of the price of the CDI one.
https://www.ebay.com/itm/174785668696?hash=item28b209a658:g:bEwAAOxyn9BRaadt
how much weight do you think you would actually save? The Verado set up at 870#s doesn't include the extra bracing you need for an Outboard conversion. Not to mention the repairs an a small block Chevy will be significantly cheaper than the Verado. Not to mention the small block will be simpler...
one other thing to ask the owner is the oil setting. That determines which oil to use. If I was buying it I would take it to a dealer and have them set the pump as rich as possible. then run the best oil you can find XD 100
Then they may not be the same block the first 9.9 were on a 13 cid block I think or 10. The 15 came out on the 15 cid block. Some work on your part is required.
3 sets of points on that motor. Same as used on Mercury and briggs and stratton. Easy to find. Vintage coils are expensive you could try Laings outboards.