Sounds like a good project. I agree with what's been said about keeping the 72 FI head. It larger diameter valves and lower compression (Volvo dropped c.r. in '72) than the '69, plus your carburator manifold will bolt right up. IPD used to sell inserts to close off B20E/F fuel injector ports at a pretty low price.

A word of advice about those Stromberg carbs - they're awful. If you plan on driving this for awhile, look for a deal on SU's with the separate aluminum manifold (I think your car has a cast-iron, one-piece, intake/exhaust manifold) and use it with the exhaust manifold and bigger exhaust system from the fuel injection car. If the Bosch FI system works, you might consider installing it. It's a pretty simple and reliable system.

Hope this helps.