No hijack; it's all good.
To begin answering you- no, I haven't attempted to estimate the power to be transmitted through my belt drive. I'll probably skip that, and use the example of existing aftermarket belt cam drives (8mm pitch, 25 mm width), which are being used satisfactorily in drag engines with
extreme loads, compared to what mine will be (close to 1" valve lifts, open valve loads up to 1,200 lbs versus my .625" lifts, open loads 590 lbs.). I've got room for 50-tooth cam sprockets, so it should work out with 30 mm width; just need to source the pieces, then machine custom hubs for my cams and crank.
I wouldn't call it "convoluted" to drive 1:2, then 1:1 to the cams. I considered that for my engine- since it would shorten the long belt spans I'll have. But in the interest of "shortness" in front of the block (also need to fit in a 3" wide blower belt), I decided against it. I've got room for idler pulleys outboard of both belt spans (about mid-span) that won't move the blower belt position ahead at all, and should control "ballooning" of the belts.
Progress on crank "fillers" testing: got the sample balanced today. Awaiting delivery of a 1 HP motor and 10" v-belt pulley (tomorrow?). Then it will be "show time"!