Tell that shop they're out of their minds, it's a 2 hour job to pull the intake manifold, clean the mating surfaces, and reassemble on a 2.3 with a carburetor.
Not only that, but even though it's aluminum, I seriously doubt the intake manifold is warped, as it has some of the thickest flanges I've ever seen.
If they're saying the manifold IS warped at the mounting flange that bolts to the head, and they installed it? they did something wrong, plain and simple, the 2.3 manifold is so foolproof a monkey with an adjustable wrench and a tube of RTV could do it well enough to keep it from leaking. If it somehow managed to warp on the car? be careful, because it was seriously overheated, and we're talking at least 290-300 degree coolant temps because the 2.3 in my race car has seen 280 on several occaisions (once for 12 laps around a 1/2 mile oval!) without warping yet.
If they're saying the mounting flange is warped where the EGR plate mounts to the manifold, use the really thick 2bbl. carburetor gasket specified for a 2bbl. 390 from a pickup from the mid-to-late 60s. These are really thick, and should seal any deformaties though you may have to cut the center out a little larger to clear the protrusion from the EGR plate. if the surface of the EGR plate that goes against the carburetor is warped, use the thick gasket found on a Chevy 350 with a 2bbl. from the early 70s, you'll have to drill out the bolt holes in that gasket a little larger/longer, but it's equally as thick as the Ford gasket I recommended between the manifold and the EGR plate, and the barrel bores are the same size/location overall on the gasket. If you're running an automatic transmission and need to use both of those thicker gaskets, you'll have to do something about the
trans kickdown rod, because the two gaskets together will raise the carburetor too far to have the kickdown rod work properly.
Clymer, Chilton, Haynes, and others ALL made service manuals for these cars over the years, the Clymer manual is by FAR the best, with the Chilton running a DISTANT second. Good luck finding any but the Haynes at a parts store these days though and most parts stores have to order it, scrounging around at used book stores, flea markets, and Ebay are how I got the five manuals I have that include Mustang II info (two are multicar manuals that cover several years/makes/models including the II, one is from Motor, the other is from Chilton), both of those are actually excellent.
If that intake is really warped, Email me @
TheRedneck84@peoplepc.com I've got an extra off of a '74 2.3 (manifolds are identical) that I'll send you for the cost of shipping, it's filthy, but in good shape and it's yours if you need/want it. I can even include one of those pesky EGR adapter plates if you want that.
I'm not running anything stock on the induction side of my '74 Mustang II (it's a street car) anymore, as the original Holley/Weber/Motorcraft 5200 carb has been replaced with a Motorcraft 2100, the EGR plate has been replaced with a 1/2" Mr. Gasket carb spacer plate, and I've modified all of it to work like it belongs there, it works far better than the original setup, but is not for the faint of heart when it comes to fabrication/modification. But I'll help you with anything you need to know about the stock stuff as I messed with it for four years before I went for broke with the bigger carb and emmissions equipment removal.
Intake Manifold Leak. Where can I get a service manual on this? 
