i believe stock sr rods can take abuse , like you say, I prefer the CA head though, but dont wanna make it a CA/SR thang.
like u say though, the stock boxes can only take so much torque before something gives.
for most daily tuned cars a well set up 400hp is enough

and like yourself kish id only ever change the stock conrods bolts on an SR lump for uprated items. Id spend my money on the metal gasket n the head, all the time as thats where the power gains are to be seen. (in addition to the common breathing mods of course).
im looking forward to tweaking my own 14a later in the year (gotta hurry up n finish my little CA first though)