For at least a bit of a reply, IRV2 member Jimelliot has info on a better water pump for the P30/454 setup that helps head off engine overheating issues.
I know what you mean on the near impossibility of access to belts and stuff on the front of the 454 in the P30 setup - the serpentine belt on ours had been just replaced before we bought it late last summer - but for some idiotic reason, the 2 V-belts were NOT changed at the same time...
They LOOK generally serviceable - but there is only one of them driving the AC compressor - and it had an annoying squeal when the AC was being used.
I tightened the adjustment enough to get it stopped, but worry about it failing at the worse time and place. I forget what else is driven off that same belt - hope it's nothing critical!
The AC compressor pulley has a 2-belt groove - but the driving pulley has only one groove - 2 driving belts sure would be better for proper drive without excessive belt tightness...
John Day....|'88 Winnebago Super Chief 27ft. Class A
Eastern .....|'88 KIT model 240 24 ft. 5er
Oregon ......|'02 Dodge/Cummins 2500 Quad Cab