The answer you want is based on how much power you want from the
engines.
Toyota has A/T transverse engined car with four, six and eight
cylinder engines in it's Toyota and Lexus line since the early 1990s.
Honda, Nissan [Infinity], Mitsubishi, Mazda make A/T transverse
engined car with four and six cylinder engines.
Ford and GM make A/T transverse engined car with four, six and eight
cylinder engines.
Chrysler make A/T transverse engined car with four and six cylinder
engines. I'm not sure about transverse eights.
You can probably put the most power through the American transmissions
most inexpensively and with the least problems.
GM is probably the best for availability of parts and price.
I believe the latest Impala SS had a transverse V8, but it's a power
on demand engine so it doesn't run on all cylinders all the time. At
max, it puts out 303 hp.
http://www.chevrolet.com/impala/#impala-ss
http://www.chevrolet.com/pop/impala/2007/v8_engine_en.jsp
However, they would be expensive to buy new and difficult to find
junkyard used and probably still expensive.
You'd probably be better off finding used 3800/3.8 V6s from mid and
large sized GM models and slightly hotrod them. You'd probably be able
to get them near 300hp for a lot less money.
In addition, there are conversion kits that allow you to connect Chevy
small blocks to Pontiac Fiero transmissions.
>> Stay informed about: Transverse Engine "Clips": Manufacturers? Years?