First of all...congrats.
I've had one of the I6's and they're as bullet proof as an engine can get. They're a very smooth running powerplant and relatively easy to maintain.
If he says it's got a "bad lifter". Fire it up with the cover off(after it's warm) and check them. Get it idling, back off each adjusting nut until you hear/feel that valve ticking then slowly tighten until it is silent, then turn your wrench 180? to set the lifter to mid bore. Move to the next one. All 12 valves should take no more than a couple of minutes. It'll splatter a little oil but it's not too bad. If you can't get one of them to quieten down I'd toss some Seafoam in the oil and run it prior to changing it. The lifter may simply be gummed up. If so, there's a good chance the Seafoam will un-stick it after running a bit. Either way...it will certainly not do any harm and will clean everything else up anyhow.
So, pull the plugs and replace them with their NGK equivalent. Then pull the cap and rotor. Check their condition and if excessively worn(contact points on the cap or rotor) replace both. IF they're not grooved...simply take a Dremel with a small wire wheel or a small wire brush and clean/shine them up. Now...establish if the dizzy still has points or if it's been converted to electronic ignition. If it's electronic...nothing else to do. IF it's still got points, time to check the gap. You should be looking for about .016" or so IIRC. Use a small file or just some cardboard to run between them to clean up any corrosion as well. Unless the wires are broken they're probably good but check all contact points at the dizzy/plug just to be sure.
After sorting out the engine, pull the out drive and replace the impeller/pump. After sitting that long it's good to see if it's hardened in place of if the vanes are still pliable. Climate/conditions will have a great effect on it's condition.
