An 8.1 is not a 454. It is a different block that 454 heads, etc do not fit on. I'm not familiar with ALL the specifics. But I recently did a little research on them for my buggy and once I started looking at performance parts availability and cost, it was quickly eliminated. Do a search on Summit for heads. You'll end up with like 4 results for the 8.1 and like 400 of the 454. They get terrible mileage, not much better than the 454, so if you ever want to upgrade the engine I would say to stay away from the 8.1. If stock power is enough than its a great choice.
They do use the same fuel system as the 4.8 / 5.3 / 6.0's. They are tune-able with HPTuners, etc.
There is no way in the world I would tow with a stock 6.0. I thought I would until I test drove one with a 6L80. I was dead-set on using a gas vehicle to tow with since I only tow my buggy now. I immediately went and bought a Cummins the next day. The 6.0's are very powerful in buggies with open exhaust, no torque management. But in stock vehicles the ECU holds them back significantly, IMO.