[xschop]

The arms themselves have to have the vulcanized rubber and inner compression ring from the rear of the factory arm machined off after being set-up in a Bridgeport mill. The RX7 arms are way thicker and lighter than the 944 alloy which is crap aluminum. I tried welding an adapter to a set of the Earliy arms and it blew thru because the alloy is too porous (crappy casting, that's why they are prone to break).
If you notice the stock RX7 control arms, they were designed with two large 12mm Dia. Grade 10 bolts and the replaceable ball joints bolt right on and off, the reason I chose them as a starting point.

As for strength, the Adapter plate is Cold rolled and annealed steel with a tensile strength of a whopping 54,000 PSI and I machined them even stronger than the RX7 factory bolt-on joints because the 944 conversion part is wider and can be used for EARLY or LATE offsets. I can even program my CNC to cut whatever offset you'd like at no extra charge.

AS for LOAD bearing, I hate to burst anyones engineering bubble, but the control arms on cars don't take the heavy loads, but the struts/springs support most the weight, it's the control arm area at the sway bar attachment points that take the beating, especially on the tracked 944. The sway bar attachment links are mounted parallel to the steel plate top or bottom if you choose to drop your X-member and Engine 1" for a lower Center of Gravity or putting in a V8 like I did. This is a far superior design than the Porsche link to cast alloy area that often breaks. Extended ball-joint pins ($200 set) on dropped/lowered cars are also scary and can bend themselves. This design eliminates them entirely.

AS for price, if you think you can build a set CORRECTLY with the right 944 control arm geometry (CMM fees are high if you can find one in your area even)......with NEW replaceable Ball joints and New Graphite-Impregnated Polyurethane and T-6061 Billet RX7 to 944 rear control arm bushing adapters for less than the $725 shipped Price tag....Knock yourself out