For brevity I will leave out the why I am messing with a CFP 90 and go to the advice of almost always avoiding the purchase of one with the possible caveat of being able to examine the specific pack in person before buying.

The busted seams issue I had known about for sometime(heard claims of shoddy sewing and/or cotton thread that would rot away) which is an easily seen issue albeit not always difficult to fix.

The issue I learned about next(and recently when given this one) is the semi diamond shaped piece of polymer(shoulder straps are sewn to it) that bolts/clamp in to a track to adjust back length can be very brittle...like milk jug out in the sun for years brittle. Get the ok from the seller before inspecting then try bending it some. If it is pliable it may be an OK example. If it breaks, walk away from it even if the seller discounts it because....

I got this one for free and the piece of plastic mentioned disintegrated so I figured like most USGI stuff parts exist to keep it running and found a shoulder strap assembly fairly quickly thar had a pliable semi diamond piece.

The length adjustment track "seemed" to be in good shape in the spots I tested it, but once I got the new strap assembly installed the track came apart in several places and due to shape and being sewn in would basically be difficult to impossible to fix making the pack dead in the water.

That being said...

If you have one/get one free, a possible work around is a MOLLE main pack shoulder strap assembly. The one I have on hand is Woodland and I think is MOLLE II, so not sure about the UCP/Multicam ones I think have slight differences.

The upper load lifter straps on the harnesses are compatible and the lower CFP90 shoulder strap adjusters will slide in to the MOLLE QR buckles after breaking the stitched end that double the webbing over.

The less certain(will fit, but not a second of time yet on durabilty) parts are the 1 vertical strap that will attach to the webbing on the rear of the CFP90 waist belt and the 4 horizontal straps on the MOLLE shoulder strap assembly by running them around the CFP90 aluminum stays in areas not covered by the nylon track the stays are inserted in to.

For someone around 5'6"(likely the lower fit range of the pack when new) the horizontal straps around the stays idea should work without modifying anything. Taller than that, the the 2 webbing tracks will require cutting open areas(and sealing the webbing cuts with heat or glue) to allow for height adjustment.

Just stuck this together so I will try to periodically pop in with sinking or still afloat updates on this.