Bummer. Sometimes those stinkers just won't go where you want them to. I have great diffuculty getting them in place with the head off due to my large fingers... suppose I should get a loooong pair of needle nose pliers.

Head off is a very good time to have the valve seats reground and the guides inspected. The seals are easy to check once the valves have been pulled and don't cost enough to sweat so they will likely be replaced (or at least a recommendation will be made by your shop to do so) when they inspect and re-grind the seats.

If the valve heads stand well into the combustion chamber (resting "on" the seat as opposed to "in" the seat) you can get them reground OK and you MIGHT be able to just lap the seat. If the valve is flush with the combustion chamber surface, count on new exhaust seats at the least (it is nearly always the exhaust as they get beat the worst for myriad reasons).

A "c" clamp type valve spring compressor is inexpensive and can save you assembly/disassembly charges. Also, you can get a good look at the parts so you know (or can make a determination) when things need to be replaced or can just be "freshened." This is important as a reputable shop will always recommend to do EVERYTHING if anything is worn so that they do not get call-back, warranty or legal trouble.

As a fer'instance, I recently had a head down to the shop and they wanted $280 for a rebuild (not bad, really) and I paid $40 to have the head disassembled, cleaned and inspected.
Next head I disassembled and cleaned myself, decided what I needed to have done and had them do it (check for cracks, face valves, back-cut valves, new exhaust seats and grind all seats 3-angle)... $160 later I have a spankin' head on the B20. Also, I was able to lap the valves in for maximum confidence.

As far as the seal is concerned, I'd just count on replacing them as a head-set should come with them.

On reassembly make sure the keepers don't touch each other (both sides) or they will not make full contact with the valve keeper grooves and you could lose a valve (not typically an issue with re-used parts but if you end up replacing any valves it must be checked).

Sorry, don't know a soul in Tacoma who cares about our old Swedish tanks.

Mike!