The inner transom plate from an OMC will not work. I just did this about 3 weeks ago; meaning I converted an OMC Cobra 3.0L to a 4.3L Volvo Penta DP-S1, including VP gimbal housing and bell. I realize your currently a Ford V-8, but as for what I'm refering to it won't matter the make of gas engine.
When I installed my OMC inner plate I realized there is no hole to run the shift cable through. The first thing I thought of was modifying it. Cutting a hole would be a major PIA due to where you would need to cut. I looked on E-bay and found a Volvo penta SX-M inner for $45.00 shipped. Since this is a winter project you have lots of time to be patient and find a good price. That said the only things that should be a problem from fire is the cable sheath and the rubber in the rear mounts, again, very cheap to aquire on e-bay.
As far as the 33c cables goes, I removed the red OMC cable ends, attached VP brass fittings, and I was able to use both cables; including eliminating the entire ESA, brackets and all, and running the original shift cable coming from the controls directly to the VP shift plate. I don't know how your controls are set up, I assume its' similar to what mine was, in that the throttle cable for the OMC pushes and the VP pulls so you have to take the controls apart and change it around.
In the end the only items that remain OMC on my change over is the engine coupler, the flywheel cover, and the trim/tilt system.
