Not that much harder (or more expensive) to convert it to an overdrive stick (M410) if you can get the parts. Worth doing if the car is otherwise nice, but be prepared to be disappointed with the gas mileage, even with OD and 3.54 axle. It may be possible to install a 240 rear axle, if so a 3.31 would be worth considering---what a highway cruiser that would be (3.31+OD)

The 75 has a few quirks of its own---a good thing is that the seats will interchange with a 240, opening lots of possibilities if the upholstery is in rough shape. The absence of vent windows is another plus---no glued on latches to fall off. The wheels are specific to that year and model. They are 15" steel, and look just like all the other late 140/164 wheels, but the offset is different, as are the front end alignment specs. This is only a problem if you need to replace ONE steelie. Make sure the new one has the same part number.Otherwise, you can use 15" (or larger) 240 or 740 wheels if you swap them all. The late engines are low compression, so down on power compared to the 10.5:1 72 E, but the upside of that is that they will tolerate regular gas, and they have hardened valve seats as standard equipment.