I always viewed the VLAR 300 as the Chevy 350 of the BattleTech universe. It was so common (6/9 in a 50, 5/8 in a 60, 4/6 in a 75 and 3/5 in the Atlas), though there should have been more mods for it. "we stroked out this 300 to a 320 to go in the Zeus, same weight but you wont get the mileage out of it."
I guess that makes the VOX 280 the Ford Ecoboost. Found in a few trucks like the Warhammer and Archer, along with a speedster or two like the Assassin and the Cicada CDA-3C.
The Nissan 200 is like the old Chrysler Slant 6. Not too sexy, but reliable and found in a lot of stuff for a long time.
The Pitban 320 is like the Ford 351 Cleveland. Yes you have a little more power, but you would have been better of going with a lighter chassis and using the 300.