Today I ran an 888SP4 on the dyno, the first of the old school hotties I've run on the new Dynobike dyno. The runs I had on the old dyno, compared to my 888, showed that the SP motors (pre SP5 anyway) really weren't anything flash power wise. So I compared today's bike with the 853 kitted 748's I've done recently. They've been 748 with 853 kits, modified combustion chambers and std ports. Pretty basic. Blue is 888SP4 with 98/102 cam timing and an eprom sort of to suit ("in progress" runs) and red is 748/853 with 111/108 cam timing and eprom to suit.
The 748/853 is certainly a nicer engine to ride, but 36 degrees less cam duration will do that.