There is only so much you can do with the interior. After all, you are dealing with 30 year old plywood that has been subject to a lot of moisture through it,s lifetime. I did strip some solid teak parts with Olympic stain stripper. About 18box a gallon. You should see the crud and dark oils leaching from the solid wood. Aft drying and a light sanding, the teak looks like the day it was milled. HOWEVER, do not attemp to strip any plywood items. I.e. bulkheads, flat panel doors, etc. The plywood will separate and bubble in a heartbeat. I got carried away and had to repair the cabinet door under the kitchen sink as it's center panel delaminated after dipping. Razor blade slits in the bubbles, injecting glue and clamping did the trick but I did learn my lesson there.
Front cabin picture shows old doors re installed on new stained teak plywood and second picture shows new stained teak plywood added to cover the bottom of the bunks. Matches kitchen galley 30 year old teak plywood pretty close.
You can work with whats there and get things pretty close. You cannot make it look like the new light wood finishes in modern boats.