I use my 318 similar to what your doing, I dont have pwr angle on the rear blade though.
H3 hyd works very nice for this with aux hyd lockout valve. You want the valve that mounts in the console to control the rockshaft. You lock the rockshaft up when using the front, this speeds up the front angle. Then unlock to use the rear blade. Works nice on mine, no getting off seat, just turn the valve. Warning though, its tedious to install the valve in the console and connect.
As for the rear blade pwr angle, another valve or a diverter valve plumbed in. Not sure about that though, havent done it myself.
Although with h3 and the lockout valve, maybe this would work.
1 spool for frt up/down
2nd spool for frt angle with lockout valve installed on this circuit for rockshaft.
3rd spool for rear blade angle.
You'd need to redo some hyd lines probably, but its possible.