If i'm understanding that crossover correctly, the two stubs with "O" rings attached mounted into the engine they are connected together fluid wise feeding the crossover pipe?
Why not (?), machine out two short ******* with "O" ring grooves inserted into an oblong thick piece of aluminum stock, cross drilled connected then plugged hole, add an aluminum 90 degree fitting shortened down with a hose barb aimed to the best direction on the engine plus add aluminum bolt down wings. Tig the parts together and install.
Figure out what's required in fittings at the opposite end of the crossover connecting hoses together again another group of aluminum parts assembled then Tig welded together. One high temp and pressure rated and braided hose connecting the two ends together. I'd damn well would of fabricated and Tig welded a solution if I owned one of these "high tech" engines. A 100% reliable cure only weak point would be the hose which should be accessible if the end fittings were properly aimed and mocked up before welding together.
I know I may come off as a wise ass, don't blame me I own the equipment to fabricate things.
Lathe, Bridgeport mill, 350 Miller Synchrowave (1993 loaded), 251 Millermatic MIg, Hypertherm Plasma, metal cutting band saws my personal home toys.
Spent a few years in a machine shop, A&P mechanic plus an electrician. This about summs it up as requirements to maintain a Land Rover without dealerships.
Making special spanner or custom tools has been keeping my LR up and running 20 years and counting.
Wild ideas come to mind like milling out a 1 1/2" thick intake spacer installed between the ram tube base and intake manifold on the 4.6 engine shifting the max torque rpm's from 3,100 to 2,715 rpm's, (per NASCAR engine computer results). Best improvement yet having 5 spd. Milled out 1/4" aluminum ring raising the plenum cover higher away from the ram tube bell ends, added clearance to the end cylinder ram tubes under the plenum cover for a cleaner straighter air flow shot. Factory bells only had 0.470" measured factory clearance from cover really sucked with airflow. Added a Pre-Oiler with relays and timer with modified sandwich adapter plus other items improving the engine's ability to live a longer life.
Accused of PLAGIARISM on one of these Land Rover forums (which one years ago?) after posting the above machined items plus the injector cleaning and testing equipment I designed and built to flush, check spray pattern as well make up a set of eight injectors flowing within 3/4% (0.0075) each other. Simulated 250 rpm's to 8,200, 5% to 95% duty cycles, 5 minute timed test events. I'll shut up and go back to was called out "antique push rod LR engines".......~~=o&o>......