Seat questions (for big and tall guys)

[macdaddy70]

I am 6'6" 320 lbs. Truck is 70 GMC with 4 on floor, original steering wheel (no p/s), gas tank in cab. It has the original bench seat with some busted springs under driver allowing me to sit lower.
I need a seat... either repair existing or get a newer model seat. I have looked at several threads on adding late model seats and I have some concerns about fitment. Mainly will they sit too high and too far forward. Same deal with repairing springs on existing. How much higher will I sit? Never done this before and not sure what to expect. Ideas or suggestions please.