Piston price is correct, they will be AA's, a Mahle copy. Hard to get without buying the barrel's as well though.
The rod to stroke ratio subject is completely mis-understood by most people.
Rod angle, thrust load and dwell times are part of the story however the main reason to alter it is to make the best use of the piston speed curve and match it to best effect with cam timing and head flow to achieve best cylinder fill and even then you can either way.
An efficient engine not being revved beyond 7000-7,500 will benefit from more dwell @ BDC = short rod.
As for stroker cranks how many do want? can do 80mm, 82mm, 84mm and 88mm in 4340 fully counterweighted with standard journal size. Rod lengths to suit N/A and forced.