Well that is an interesting and pleasant twist.
If we set HP growth for base class to be 8, which is assured through level 10, and then you're a full time HPC class of 15, the HP at 50 is 232 compared to the 288 of an 8 HPC class (at 140 multipliers all around), and a gap of 50 is far more paletteable.
However, the twist to this is that enemy units still suffer from this 100 HP gap. If we wanted to make enemies not as affected, and assuming a 50 HP gap is ideal, then to match up with an 8 HPC @ 140 HPM at level 50, the lowest growth can be is either 10 (44 gap) or 11 (61 gap).
Ultimately I still think HP needs to be boosted through either growth, multipliers, and/or equips -- or WP/PA/MA reduced, so things are less one-shotty than in normal FFT and 1.3, but this is just me projecting here. I think all your WP's are a bit lower, which is welcome -- spells can be curbed with X's and Y's, and then all we'd need to do is curb bare-fisted output and we're money... maybe.
A more radical shift would be what zodiac brought up in a discussion about CoP -- high stats are awesome because they allow for a lot more wiggle room. In low stats, a single point drop in PA plays out drastically different with modifiers like attack up and protect in place. But when the total PA is like 30, losing a point or two really doesn't provide that level of offset by percentage. So a unit doing 150 damage to a 300 HP unit has the same effect as a unit doing 300 damage to a 600 HP unit, in the grand scheme of things, but the latter simply flows a lot better, math wise. Only wrench are enemy boss units, because then they're either capped at 999 with equips or go up to the ???/1000+ level, but even ???'s are able to equip weapons, shields, and accessories provided there isn't HP boosting present.
I know I'm making two simultaneous proposals, but I think they both have merit. Or, if you don't like, just stick to the either 10 or 11 for HPC gappage. And while Ramza can get his pre-HP stat modified, Rad will be subjected to growth in whatever class he's in, which seeds all future growth notably.