I have one of the Iraqi Malibus that GM of Canada built for shipment to Iraq in 1981. These cars were equipped with the Chev 229 V6 and the 3 speed Saginaw manual transmission. The plan for this car (when I get around to it), is to swap in a late '80s 4.3 V6, and a 5 speed from an '80s S10. One of the advantages of using this car, is that its already equipped with all of the manual transmission bits & pieces, so there's no hunting around for those parts, and the engine mounts are already set up for a 90 degree Chev V6. I've done some reading on other forums, where people say that the input shaft on the S10 5 speed is approximately 5/8"-3/4" too long to fit properly in the 90 degree Chev bellhousing, and into the crankshaft on either the 90 degree Chev V6, or the Chev small block V8. In most cases where this issue comes up, the person posting just cuts the appropriate amount of material off the input shaft of the S10 transmission, and this has solved their problem. There is a company called Hamilton Intakes, that manufactures a spacer plate that installs between the bellhousing and the S10 T5, that spaces the 5 speed back the proper amount to correct the issue with the length of the input shaft on the S10 trans. I haven't had any personal experience with this just yet, so I can't confirm this issue. The shifter on the S10 transmission should come through the floor in approximately the same location as the shifter for the 3 speed, but once again, I can't verify that just yet.
I want to keep this car carbureted, so I tracked down a factory cast iron GM 4 barrel intake from an '85-'86 light duty truck (here in Ontario, emission controls are required by law), and I've got the factory tubular exhaust manifolds for the 4.3, that GM used in the mid to late '80s. The engine block for the 4.3 that I have has the mounting pad for the mechanical fuel pump, but the bolts holes for mounting the pump aren't drilled and tapped, and the hole for the fuel pump push rod has to be drilled (spoke to a local machine shop guy, and he tells me that since some 4.3s were used for marine engines with carburetors, that this shouldn't be a problem). The later 4.3 engines have the provisions for a newer style serpentine belt drive system, so I'm going to try that as well.
The Malibu chassis will accept most, if not all, of the popular suspension and brake upgrades for the A/G body cars, and I'm figuring that since there will be less weight on the front wheels, that handling should be a bit better than a V8 equipped car. The goal for the 4.3 will be something around 200-225HP. This should be within the limits of the S10 trans. I have an '84 Monte SS, and the 305HO in it was rated at 180HP from the factory, so I think that a 200HP goal for a 4.3 is realistic, and should provide a car that's fun to drive, and not too bad, in terms of fuel economy.
I don't want to build a race car, just something that's fun to drive, and a bit different.
If you decide to try something similiar, please keep us updated with your progress. Good luck.