I've used the Holley gen 3 swap stuff a few times since they've come out. Their mounts seem nice, and position engine well. Their exhaust manifolds fit well if you have clearance issues. The headers fit well, with the standard box or Borgeson box. I ended up putting one dimple in a pipe for box clearance. No header issues with the low mount a/c pumps.
My latest swap, for me anyway, is a 6.4 in a 67 charger. Holley mounts, headers, even the full exhaust offered by holley/hooker fit well. I had some issues with the trans mount and h-pipe, but that was because of my choice using a gear vendors on the back of the 727.
I also used their terminator x max controller system. It was easy to deal with, even for someone not used to a system that is so tunable. I'd only used the plug n play stuff in the past, like Hotwire or Mopar.
Setup was easy, no real programing needed. The 6.4 is a stock crate motor, and they had a stock 6.4 tune built in, so it fired right up and purred. I haven't driven it yet, but seems nice.
I even used their 12.3inch pro dash for gauges. Even that was fairly simple
With products like these, and fuel tanks like Tanks Inc and others like it, the whole swap is simple.
A few tricks to learn in the beginning when bolting items on the engine, like the pan and starter clearance to the block......things like that.
