The Sunbird can readily accept any GM 60 degree V6 or GM 4-cylinder engine including Quad4 and Ecotec engines. GM 90 degree V6 and Cadillac 4.1,4.5,4.9 engines will also fit, but only if you have a big hammer and are willing to deal with some fun suspension issues.

yes the 60 degree v6s and the 90 degree v6s share the 60 degree bell gousing pattern

Yes, and no... GM and Isuzu are partners to some degree. I personly have a '97 Rodeo, and am looking to install a bigger better engine, and have come across several interresting facts. The Isuzu 3.2 liter uses the GM 60 degree V6 bolt pattern to the transmission, as well as obviously the GM V6's do. Currently searching for an '04 3.8 liter pushrod V6 that will use my ignition system (coil on plug) and the MPFI.

This engine is based on the 60 degree V6 (2.8,3.1) are the most common. It is a dual cam engine based on that block. It suffers a common issue with a plastic intake manifold gasket, usually goes between 75-100k miles. If not taken care of, eventually the cam will loose lubrication, seize and your engine will be shot..

The 4.3L V6 GM engine does not have a timing belt it has a chain, and it does not directly drive the distributor.