Like a lot of people, the allure of a cross ram hit me in fall of '71, when I looked at a cross ram equipped '69 Z for sale locally ($2500 if you can believe it, car was involved in a messy divorce proceedings). Several years ago I started altering Offenhauser cross rams to emulate the Winters original, machining the top and "reskinning" it to remove the milling feed lines. They turn out very close to originals, the biggest difference is the size of the top bolts (1/4" Offenhauser, 5/16" originals), there is a minute difference in the gasketing, but overall they will pass inspection at first glance if you don't mind the missing logo. Carbs are 600 cfm DP Holleys, match the 4295 original flow rating, you'll need to jet and power valve as original 4295 specs. Everything else is available as reproduction (air cleaners, fuel lines, brackets and cables). The oil fill tube repro that's available is a '68 pattern, the (parts book) listed '69 fill tube is not currently reproduced. I've completed several of these, sold a couple locally and some on eBay. If you scrounge, you can build a good unit complete for about $1500-$2000, and depending on exhaust and tune (work best with headers and non-point ignition): they are impressive, and are sure to draw a lot of attention no matter where you are.
Current reproduction cross ram units run around $2500 for the manifold, but it's mighty close to the originals. Some people have had problems with the valve cover clearance when using stock aluminum GM covers, especially if your heads are milled - the fix is to use a set af later covers and machine the upper gasket rail to clear the manifold. I don't think I would recommend milling an original set of covers unless you have a bunch of NOS parts you don't mind altering.
If your after the look and feel, but not the numbers, that's the best way I know of to do it -
Regards,
Steve