"Stroker kit"...hehe..the guy is stroking something! FWIW, a 4.000" bore, 3.400" stroke 4.1 is 256 ci, not 265. Maybe he's dyslexic.
Those pistons will result in a 8.9:1 CR motor with a nominal 45 cc chamber. Some of us like that, but it's unlikely to be a 16 psi boost pump gas motor. They are 351W stroker (416") pistons designed for use with a Chrysler rod bushed to a SBC pin..mostly irrelevant as they actually measure out nicely for use in a long rod 4.1 (pin height of 1.310" results in a stackup that's .020" in the hole). If I were going to roll the dice and run those pistons, I'd run them with a BIG ring gap. KB even has a special technical note recommending this.
The other problem with that particular auction is that those Oliver rods are almost certainly wide journal rods...he doesn't specify. If so, they'll need to be narrowed or a wide journal crank will have to be used ($$$). Nice rods, though!
CTX, the longer rods have several effects. They reduce piston speed and side loading, and generally raise the powerband. There are arguments on both sides as to whether short or long rod motors are better. It's a fact that probably every BIG horsepower S2 Buick ever built had longer than stock rods, though.
Avoid any rod longer than 6.5; there are a lot of 6.65 rods out there but with a 3.4" or longer stroke, the piston compression height required is too short for a reasonable ring stack.
