Since the stovebolt connecting rod has a pinch bolt in the top end, the wrist pin only has to be rough centered in the pin bosses- - - - -no end clips in the pistons are needed. According to my Silvolite catalog, the #1718 piston has a compression height of 1.843" and a wrist pin diameter of 0.875". The stovebolt wrist pin is a 0.865" diameter, with a 2.060" compression height. The compression height of the 215 piston is just enough shorter to compensate for the longer stroke and shorter deck height, while keeping the piston top close enough to the top of the block to maintain good compression pressure. The Buick piston also has a shallow recess, which could be used to adjust the deck height by machining the top of the piston a little if necessary. The only downside is the wrist pin offset- - - -the 215 piston is on center, and the stovebolt piston has a slight offset. That MIGHT result in a slight piston slap, depending on where the ignition timing is set. Fitting the pistons with a fairly tight skirt clearance would tend to minimize that problem.
I'm in the process of fabricating a milling fixture that centers up in the #3 main bearing bore and can be used in a floor mount drill press to do the main web narrowing- - - -line boring should not be necessary. It uses a 3 1/2" diameter shell milling cutter to machine an equal amount of material from both sides of the thrust face of the block and main bearing cap. However, I do have a portable line bore machine if I decide to do the full bottom end rehab.
Jerry
