why do you want togo through all that troble of swaping and put in a non toyota 6 aleast go v8 I get better gas mileage with my v8 than a 6 but it will cost the same for either swap but ford may cost more
The 300 is a great motor. Reliable as a rock and you can get them EFI. The I-6 is also a great configuration. It has lots of advantages over a v-8 as far as reliability, balance and stump pulling torque. Weight, horsepower and size are generally not so good. There are not so many performance upgrades for the 300 as the 302, but it is a fine choice for a LC if you want to drive it or crawl it. I wouldn't choose it as a mud boggin motor.
Your big obsticals are going to be finding others who have done it and parts to do it with. This is not a bad thing if you want to be unique or ground breaking, but you better have deep pockets and patience. Little things like how to fab a throttle cable, or where to mount the air cleaner will make the project bigger than something that's been done before.
Overall, I would say this conversion is not for me. Not enough advantages to offset either a 2F rebuild or a 350 conversion. If you're a big Ford fan, like I-6s, have a wrecked late model F-250 - maybe it would be worth it, but I think when you go to show it off or sell it lots of folks will be asking you why you went through all that work for that motor.
Of course that's all just my not-so-humble opinion, YMMV