[dana44]

Aftermarket can take care of the third member for the 7.25 these days as noted, the 8.75s for the A bodies are not too difficult to find, small bolt pattern is usually why they are easier to find, but that can be changed if you like, just keep your eyes open for one. Simply opening the stock heads with 1.88 stock 360 valves is a biggie, and the bore can handle them, porting is definitely a positive for more than 40hp even if the rest of it is stock. Just don't drop 360 or 340 heads on her, drop in compression is too great. Crank should have no problem holding up to a turbo if you go that route, it is a steel crank, same as the 318 actually, (even though there are some early 273 years that have a different bolt pattern for the flywheel if not mistaken), so not a difficult item to find, replace or get bearings for. I believe the cams were solid with adjustable rockers, which is a positive, and I think you could change that over to a hydraulic cam and different pushrods to have better adjustment. Make sure the Air grabber intake is for a 318, not a 360, port size is different and messes up flow if they don't leak.

 

[dana44]

The 8.75 found in a Dart, Duster, Demon, actually all the A bodies through what, 1975 (help me out on the end date), gives you a lot of room to look for one. Most of the time it is the fact the A body rear end is the smaller bolt pattern allows them to sit around a lot longer than the few/rare large bolt pattern. They are out there, they are fairly available, just keep looking. As a good side note, the third member 8.75 is the same for all 8.75 rear ends, housing and axles are specific due to the width.

 

[dana44]

The 273 will take any 318 and a lot of 360 bolt-ons. Cam is not a big deal, but a little extra lift is always a good power builder. Windage tray is always nice and an easy modification/addition, high volume oil pump, a 318 performance intake, not a 360 manifold, is good for more breathing, good rings and bearings, one thing that works every single time to gain easy pep, power, and mileage, is porting the heads (but don't polish them for street driving).