30 year old Gold Metallic is going to be difficult. Mainly because 30 years of sun will have bleached the color out somewhat. If it's been garage kept you'll stand a better chance than if it's been outside it's whole life. DBC should match nicely to the car, check for alternates, your jobber will have a deck of them if there is one for you car. But because of the age of the paint it's not going to matter much. I would probably just go with the "Prime" formula. I would not use the PPG Prophet because it can be notoriously inaccurate and you have a paint code, plus 1988 is in the modern era so color match to
New OEM paint should be very close. Irregardless here is how I would proceed, first repair your damage, do any necessary bodywork etc. etc. If you've done work on both doors then use you fender as your main blend panel. Considering the body style of the Volvo and the fact that it's 30 year old paint, I would plan on coloring the entire side and blending into the top of the fender where it meets the hood.
So once you have everything prepped, seal your primed areas, you can choose to not seal and base over your primer but with DBC and gold metallic you need to finish with 800 wet if you plan to do that. I would spot seal being careful to sweep in,sweep off, so that the sealer blends out and doesn't leave a noticeable start stop area around it. Base the side (minus the fender), medium coats, not too wet. Focus on sweeping out with your gun at the end of each pass onto the fender. Carry each coat out a little further onto the fender. DBC will take minimum 3 coats spraying medium, more like 4. After your have coverage on the side(minus the fender), use some DBC500 or SPI Intercoat and mix it 1:1 with your already reduced basecoat. If you don't have either in a pinch you can use reducer (be sure you are using either SPI or PPG DT and use a slow reducer, slowest you can get away with) I would use either SPI885 or DT885. SPI reducers are actually better than the DT I've noticed a difference in how DBC lays down with the SPI reducer.
With your Intercoat reduced base, proceed to start somewhere in the middle to back of the front door and carry into the fender, sweeping in, sweeping off. Each back and forth pass should end in a slightly different spot. Actually with that fender carry the color all the way to the end of the fender. Your main concern is the very top of the fender before it bends to meet the hood. (hope that makes sense)
Simply carry it almost to the top of the vertical but not quite. Keep your line nice and straight when spraying there. If you do it right it will blend itself. Apply 2-3coats like this and see how it looks. Look for difference in
color in the blend area.With gold you need to look for the metallic laying down with little to no mottling as well.. Relax your eyes and try to see if the color transitions nicely, texture and gloss differences may be noticeable but that doesn't matter clear will hide that.
Then clear the entire side. Good Luck.
PS: When I say sweep in, sweep out, it should be a subtle, not exaggerated motion. Basiclly you are trying to pull off and feather off the trigger subtly at the same time.