I had for alittle over a year a 69 26' excaliber (sold it last year) , spent most of the time looking high and low for info on it but came up short.
I do know the design is one of Crelocks early works, it was/is a quick and fast little boat, as far as the motor config goes, it's a OB in a eng well, BUT, not all OB's will work, I was able to drop in a new 20" shafted 5hp merc 4 stroke and that was about perfect, however, make sure it exhausts threw the prop, mine did not and it was too loud IMO.
We kinda wish we had kept it, awsome little boat, classic lines and a total blast to sail; I had a buddy in Dana Point 5 slips up from me who had a 68 that he has been racing for years and does really well
Sorry,not much help, but you gotcha a very sweet boat
1955 Blanchard 51 Custom ( I got a woody )
On the 8th day God created sailors and evil stood at attention