My experience with the bottom paint on my Explorer was no stripper could touch it. I ended up getting it sand blasted off. An experienced sand blaster knows how to adjust the pressure so not to hurt the gelcoat. Another option is to get it blasted with walnut shells (Seems easier to find in the North).
My boat lives on a trailer, so I didn't think about a barrier. I used Petit Vivid and it came out nice.
Be careful about using Copper in the paint - not good for the marine environment.

Is the liner bonded to the hull side on early 70s 19-6? Also, is it tabbed to the floor? Just started a project. Already itchy.

I see. If it was me I would measure from the pivot point on the motor to the top of the cowling to get the clearance needed for full tilt.
This guy built his extension 36" and has twin 350 Yamahas on it. He also added a jackplate to be able to tweek how the boat runs. He gets 50+ mph out of her.
https://www.community.boatbuildercentral.com/forum/viewtopic.php?p=510075#p510075

Have you considered adding a flotation bracket, like made by Armstrong? https://www.armstrongnautical.com/armstrong-outboard-brackets/

Hi All,

I have pushed the button on closing the transom on my 1986 250xf and having a extension bracket being built to hang 2x Suzuki DF250's. Its being built into the hull and stringers in fibreglass and will extend out from the keel for the benefit of additional buoyancy.
At present I only have one Suzuki DF250, but thought it wise to make provision for more power in the future.

The question I wanted to ask, is what is the generally safe accepted transom extension to allow a safe full tilt with a Suzuki DF250? I have read that 26" is tight and most go for 30" to be safe with the V6 motor.

Appreciate if anyone can point me to the answer on this? I'm thinking 30" would be wise as it's guaranteed to fit.

Cheers

Jonathon