Hi. Funny you should ask about headlights....

re: "...if i get a full headlight assembly from an older volvo with the 4 headlights (two on a side), is it possible to replace my 2 big headlights, and how hard would it be to do the converson?..."

I can appreciate your interest -- I'm assuming that you want better lighting -- I, too, have a '86-93 series car with the big headlights. I've always (for about 3 decades, now) used Cibie substitutes for sealed beams, as I have currently on my '84 240. But now, with a '93 240, I'm trying to get Euroheadlights to get the same performance (and to keep the "large" format styling).

But incidental to my search, I've learned that you cannot interchange pre-'86 lights (such as the quads of an '84) on a '86-on car, as the sheetmetal around the parking lights are different, and you can't combine the newer parking lights which fit the sheetmetal with the older lights because of mounting or attachment problems.

Unless you want to go to Euroheadlights, as I'm searching for, your only option is to get a part from Volvo trucks that allows you to substitute your big headlights with a large fascia that accepts a 7" round sealed beam. Then you can install a Cibie (or other european brand) H4 headlight in its place. You'll lose the "looks" of the large headlights, but you'll have really great lighting (that 7" round, in a Cibie, is incomparable -- I had a set in my old 164, and it's still unsurpassed).

Good luck.