80 Series 4500 - New Head vs Rebuild Cost

Hi All,

I got a call y'day arvo from the engine rebuilder, my head is in poor condition. They can see excessive corrosion visually!

The deal is that my head is non-repairable. They suggest either a brand new - built with same lpg rated valves & seats or a wrecker's yard head job and rebuild that.
New cost would be $4000, used $2500.
Toyota price new (but loose parts) is $3650 + build (estimate) $700.

Looking around for other ideas too, rebuild original head with bolts & gasket, say $700 then sell car (not preferred). Or check the wrecker's head (say $150), fit & wait till it deteriorates then have the same discussion again??

Any constructive ideas would be appreciated.
Cheers
Bob