Hi Duncan,
One good source of WW information is Dayton Wire Wheel
http://www.daytonwirewheels.com/index.htm
or
British Wire Wheel
http://www.britishwirewheel.com/
Over the years, I have purchased 3 sets of WW's for my E-Type
1. Dayton 15x6 HD SS spokes std lace
2. MWS 15x6.5 Center lace HD SS spokes
3. Dayton 15x7 Center lace Alloy rim HD SS spokes (on car now)
All three sets where for tubeless tires
The Dayton's were truer and didn't leak
What I've learned from the WW wheel experts:
Stay away from chromed spokes ... they're brittle and tend to brake.
Polished alloy rims w/SS spokes look great and don't rust
205/70 SR 15s s/b on a 6" wide rim
Never try to tighten spokes on a tubless (sealed) rim
From personal experience, I've found:
Center laced 6" rims with 205/70 SR 15s have enough offset to not cause clearance problems in the rear.
Center laced wheels provide for better handling (wider track)
Std laced 6" rims with 205/70 SR 15s will impact the bump-stops, and possibly the bump-stop mounts
With that said; fitment will vary from car-to-car.
Hope this help.,
Cheers,