Front seal: pretty easy - although you'd have to remove all the belts, with a blown front seal the timing belt might be contaminated anyway and due for change. Not a big deal.

Burnt valve: These engines are easy to work on - 8 nuts and the exhaust manifold can be taken off and lowered down the side of the block, another 8 nuts plus a couple of bolts and the intake manifold can be taken off and pulled to the side. Doing it carefully and by the book I'd say you could have the head off in about 2 hours. That includes taking the belts off in an orderly way and preparing your way towards ease of putting it back together; in a pick'n'pull type setup, slashing the belts and breaking the cover, you could have it off in about half an hour or less. Swap a new valve in if the valve seat is still good, or have a machine shop put a new seat in. A slight skim to ensure a good mating surface ($30 or so) and you'll be set to put it back together again. Use the new style angle tighten bolt (cheap or free at the P'n'P) if yours is pre-'85 to save the bother of having to retighten them and all that.

About a days work if you go easy and careful.

Cost: About $60 for the head gasket kit (you can use a Scantech kit, but use Elring, Reintz or another good brand for the actual head gasket!), $30 for skimming, $5 for the seal (or change them all for $15), $25 to change the valve (or DIY), if the seat is scrap about $40 to change the seat, or grab a head from the P'n'P for (I guess) about $50-$75. While you're in there, change the timing belt ($10), check or just replace the tensioner ($20), and feel/check the water pump (probably OK, but impossible to feel if the belts are on).

Round it up (solvents, coolant, oil, etc) to about $200 for parts and count on a days work.

At that price, in good condition and with working AC, I'd snap it up if I were closer. If that is _really_ the only problem it'd be a pretty good bargain.

Bram