I've been getting my 3D printed Merlin engine pieces from Craig at Spartacus Boatworks. I met him at the Hydroplane and Raceboat Museum when he was taking measurements of the Merlins and Griffon for accuracy. I have Merlin parts for my 83 Atlas and just got some Griffon style exhaust stacks for...
This is from an 1/8 scale hull I picked up years ago. Looking to get $125 plus shipping for it. I can take more pics or take measurements if you're serious about picking this up.