I've never heard of ether one of the chassis builder but there are hundreds of people building frames and if it looks good go for it. Straight axle or dropped,I prefer dropped myself but it depends on what style car your building. As for rear axle you can't go wrong with a 9" Ford. HRP
I'm a very satisfied Gary Maxwell, Blackboard Hot Rods, customer. He built a very accurate frame jig and tig welds all components. Plus he's a great guy to deal with, you won't be unhappy.
I believe Gary Maxwell would be Blackboard Hot Rods and Duane Jones would be Kiwi Konnection and as far as I have heard , both have great reputations. http://blackboardhotrods.com/ http://kiwikonnection.org/
This is going off the reservation but I like coil springs on the rear especially on a short wheelbase vehicle. I think it is a left over '60s thing.
Most folks couldn't tell the difference between the two chassis. Maxwell worked at Kiwi Konnection when Squeak Bell owned it, Jones bought the business from Bell. I bought a frame from Jones shortly after he bought KK and love it! The welds are great, and the attention to detail was very good.
Another style you might consider is 1/4 elliptic springs in the rear. If you are worried about cornering more than ride I would lean away from the buggy style spring unless you plan on sway bars.
You need to check out Gary at CORNHUSKER HOT RODS in Nebraska. He builds a killer 32 frame at a great price. Plus it is set up the right way.