Cheap 318 performance mods.

My experience of pulling wrenches for 30 years points not to the Magnum having less cylinder wear than the LA engines because of design. All manufacturers engines took a substantial leap in engine life with the introduction of EFI. The throttle body systems improved fuel atomization so wear was reduced due to less cylinder wall washing. Where the real jump ahead was going to sequential multiport EFI. This really tightened up fuel metering and distribution. The pressure the fuel is injected at went from 15PSI to around 50PSI which created much better atomization. If you put the SEFI from a Magnum on a rebuilt 273 or 318 LA, I see no reason they would not last 300k miles of daily driving. NOTE: DISCLAMER on that, not a race engine! Modern piston ring technology and materials with the current plateau honing cylinder finish is also a good start on the process.