HP5+ is correctly available in 8x10 but is not very good for alternative processes such as Platinum Paladium.
I keep hearing/reading this, but I have to disagree. in ABC Pyro (and possibly in other staining developers as well) it can build extreme density. I have made a couple of vandyke prints from HP5+ negatives developed in ABC 1+1+1+7. One negative was too contrasty even for vandyke! I have no experience with platinum, but I understand it requires a contrast index somewhat lower than vandyke or salt prints, so I think that if HP5+ is good enough for vandyke it should be good enough for platinum.