There a few things to keep in mind. The size and shape of the hole in the transom, is it smaller than the outdrive you plan to install or you will be adding material to support the transom/shield. I have done some OMC to Volvo conversion and we would have to completely rebuild the transom and then cut a new hole for the Volvo drive.
Volvo would be my choice as you can use any drive from the 250 to the 280. If you are looking for the tilt and trim option than you would have move into the Volvo 290 series or find a T model of the other models to gain the hydraulic tilt cylinders. The other models used the electrical/mechanical tilt system, not the best but usable.
You will need a Volvo flywheel cover for the Ford small block engine, I doubt your flywheel cover would fit the Volvo drives.
Prior to Volvo selling there engines/drives directly in this country they had agreements with various engine suppliers to sell the Volvo drive with those suppliers engines. The marine engine suppliers of those days like Chris Craft, Crusader, Chrysler, even Wausau engine got into the act. The different companies used their version of the flywheel cover to attach the engine to the drive but all of them would were similar and usable on your engine. Ford were not used as much as the Chevy 350 but you find them. I remember seeing a Ford flywheel cover produced by Wausau engine that was a couple of steps up from what was available from any other company. Volvo started marketing their own engines/drives by the mid 70's and you started seeing less and less from the other engine companies. Volvo did use the Ford engine but not in the numbers they used the Chevy.
You will need the exhaust collector for the V8 engine unless you plan on running straight exhaust out the transom. There is various way to accomplish that task but it is easier to get it all as package when you find the transom shield and the drive.
FYI, before I forget, none of this means much if you can not get the drive attached to the hull at the level that will allow the engine to line up with the drive. Bringing up the engine a bit to line up with the drive would not be much of a problem but if it has to lowered in between the stringers that may be more of a issue.
Good luck on your project.