I have the same project going on on my 38 Ocean. The original SL Sprint 1000 died after 23 years of use. I replaced it with a Lewmar V1 (based on the Sprint 1000-supposedly a direct replacement). There are two differences between the old and the new. One, the mounting bolts are directly around the under deck motor on the V1 vs.around the perimeter on the Sprint and the new up/down solenoid has a three wire control).
To solve these issues I grabbed a scrap of 1/8 inch 316L stainless plate at work, downloaded the cut diagram from Lewmar, and made a big, under deck mounting plate using our waterjet cutter. The original solenoid controller was directly behind the 12V distribution panel in the nav station. I jumpered the 1/0 wires to get them to continue to the bow, added a breaker, replacing the hard fuse that was on the original.
From the photos you can see the outline of the original windlass with its wide mounting bolts in redtgreen sharpie, and the new 316L plate with close in mounting bolts. The plate will be secured to the deck from the underside, secured in the dry, fwd lazzerette (behind anchor locker) above the new motor. The new solenoid will be bulkhead mounted in the same dry laz next to the motor.
I learned when the old one failed that the manual retrieval gypsy is a $250US option. That will be on the new one.
One more tip, search youtube for your windlass model. Other installers will no doubt have helpful tips.