I agree on the shorter piston - the tensile (fatal breaking) load on the rod is pretty much a function of the recip weight, and reducing it by 1/3 or more is a big step forward.
The rod ratio is much better, but it's preferable to the strokers using the 292 rod (which is worse, and with a smaller pin).
Trying to do trig mentally is ^%#${@!!, but... since the rod angles at every point are almost the same (rod ratio determines the angle), and the pin is only bumped over by 3/32", I agree that the cam clearance should only be slightly less.
On the cam: I know that some exhaust bias was effective back in the day and (JMO) probably still true, but the flow data posted recently on the 235 cause me to question all of it.
The split between the 848 as-is and well done show much more intake improvement than exhaust. From this I conclude that a highly modified engine wants even more exhaust bias than a hot-rodded stock head.
I'd leave the event split for now, until you can have the head flowed. You may out to be on the money (can't be too far off), but the results might be better.
Is this specifically a VW Type I grind? I.e., requires a 31mm tappet?
The stock GMC rockers don't impress me, especially with higher speed and more spring, but I'm not sure what will work. The similar Slant 6 (laminated) rockers have been stiffened back-in-the-day by simply spot-welding plates to both sides across the bridge above the shaft, drill through the plates first for rosette penetration.
AFAIK the GMC is about 3-3/8" long O/A, which is huge vs. automotive stuff (except Chrysler hemi exhaust). There's probably something for a tractor or Waukesha that's close but I haven't found anything. One good thing is that the pushrod and valve are parallel, which certainly isn't common in modern engines.
BHJ: I'd ask them if your longer crank length and stroke length changes the frequency much (stock 235 estimated at 216 Hz). They may be willing to slightly mod the rubber to adjust without $$$.
