When I heated molded my liners, I did not tighten the laces. When I ski I do not tighten the laces. Only cinch them enough so they don't flop around in the wind. They have plenty of support when skiing but can step right out of the shells with the liners on my feet and the end of my set.
Here's some used XL Radar vectors for cheap
http://www.ski-it-again.com/php/skiitagain.php?topic=Search&category=Bindings&postid=23022
Or he could get a New Vector and RTP for $155 shipped
http://www.wakehouse.com/products/radar-vector-feather-frame-water-ski-binding-2012.html
http://www.wakehouse.com/products/radar-adjustable-rear-toe-plate-rtp-2012.html
Just checked and the fin block on my senate C is just like yours. So the replacement ski might come the same way. Maybe just file the sharp machined edge and go with it. As for sizing a ski for the wife.....best of luck.
I found the standard Senate provides a "damper" ride which can be nice in choppy/rough open water. The Senate C is more "responsive" and quicker cross course. They both are at home in open water or in the course, the Senate C just has a little higher potential in the course.
As for double boots or single and rtp, go with what you are comfortable skiing with now.
@kmenard given you're fighting for good water on a public lake, the standard Senate should be fine. With that said, if the extra $100 isn't an issue, you'll appreciate the Senate C once you get hooked on chasing bouys.
I have using the sportube 3. I staggered the skis so the bindings fit together like teeth on gears. The tube ended up a little longer but it gave more room on the sides for wetsuits, vests, and towels for padding.
@mikey What speed are you skiing at? If 32-34, the Radar Senate might be a good choice. You don't necessarily need the "C" version if open water skiing or just learning the course. If skiing slower the Radar Theory could be a good choice as well. I found 2012 models of each at this site for within your budget. http://www.wakehouse.com/radar-water-skis/
If he's just about getting through the course on a 65 synchro a 65 senate C might be good for him and give him something to grow into. Can't say it would be better than some of the other suggestions but found a good price on one here http://www.wakehouse.com/products/radar-senate-c-slalom-water-ski-2012.html
@tfriess yes, a basic tape measure will do. Just measure from the tail of the ski to the lowest stitch line on the heal of the front boot. It's easier to do the first time without the rear boot mounted to the sequence plate.
@countymountie 8-10 minutes at 250 F. Make sure you remove the insoles while heating. And yes, the newer sequence plate is a little thicker to prevent bending.