Cab to suit Warwick profet 3.3 head

[gizmo6789]

I own a Warwick ProFet 3.3 head.
It delivers 300W at 4 Ohms.

can any one recommend a cab to go with it. Im currently looking at a Gallien Krueger 410BLX which is 400W at 8 ohms.
OR
A Peavey TVX 410 EX which has 350 Watts continuous, 700 Watts program. at 4 Ohms. but also available at 8 ohms.

can any one help me out.

also whats the deal with losing power between a 4 ohm head and an 8 ohm cab.

Thanks