Dale, you'll have to excuse my friends. They have undeveloped manhoods so they resort to picking on teenagers on the internet so they don't feel so inept.
The project you are looking at doing is going to cost you more money than you expect and result in a very heavy and poorly performing ski. The wave raider is wide and heavy. It has a few right parts, like fixed steer and a 701 motor, but it's going to be too heavy for a stock 701 motor to push. You are basically trying to turn the waveraider into a B2, or a really fat B1 or X2.
You under estimate the project you wish to persue here. You will have to work with epoxy resin for this project. Epoxy is about $60usd per gallon. You will need one gallon, maybe 2. If you just cut the back and close it up, a half gallon might cut it, but by the time you are done shortening the hull, chopping the seat, pouring foam, shaping out the new design, laying up glass, and etc, you are looking at a very large investment.
I am novice with composites, and if I were to be doing the job you are suggesting, and if I were to do it right (Shorten, seat, etc), i would estimate about 0.5-1 gallon of 2lb foam ($30), 6 yards of glass (about $8 per yard, call it $60), 2 gallons of epoxy ($120), a couple of sawsall blades, sand paper, etc misc expenses ($100). I'm no expert but I'm guessing these mods you are talking about are going to end up costing in excess of $300, more likely into the $500 range after mistakes and etc. You still need to apply a body filler, sand, prep, paint. You could be easily $500-$1000usd by the time you are making this hull into something nice.
This doesn't include the opportunity costs of doing this build. By doing this build, you are missing out on potential work, chores, mowing lawns. To give you an idea, my X2 has about 200 hours and $400 in composite work. That doesn't include sand paper, etc. If I had been at work for every hour I worked on my X2 over the past 5 years, I could have a BOB hull or similar.
By the time you are done buying a waveraider, making it into what you want, you will have spent enough time and money that you could have bought a wave blaster 1. In addition, you will have a boat that is heavier and under performs compared to a wave blaster. The only benefit is that you will have learned how to work with composites, at the cost of never riding your jet ski.
The ski you want is a Waveblaster 1 or a X2. If you can't afford them, then you need to be patient and ride something else. The pole ski may not be preferred but you have to pay your dues. I rode a broken 650sx, then a broken X2. Now I have a nice SJ and am about to roll out a very impressive X2. y only regret is that I spent a bunch of time over the last 5 years working on my X2. if I had just parted out my X2 and 650 stuff, I would have been able to buy my SJ over 4 years ago (Blaster in your case). The only bright side of this is the amount of knowledge and experience I have obtained over the last few years. I would have rather been riding. This may work out good because of how my X2 will turn out, and what I plan to do for my real race hull once my X2 is done, but we're talking about hundreds of hours and thousands of dollars invested so I can be less than spectacular at riding.