OK i got this email from the Guy at the works Factory who has been doing us some trick deals on shocks lately.
"I can build you a Vintage MX build which would be 14.0 long, with 3.75 inch travel at the shaft. This would keep you within the 4 inch wheel travel limit for pre 75 or whatever travel or E2E you want really.
If I can make it with the welded steel bodies, I can offer a better discount again of 30% on your price, since we discontinued welding them and started screwing eye/body assemblies together like the ones you already have. We still have a few on hand for the length required for your shocks.
One thing I would change on the current build is to put floating pistons internally so that you could run them upside down, and use a slightly shorter spring stack to clear the chains.
If you want a single progressive rate spring I can build that shock for 455.00, discount it to 320.00
If you want a dual rate spring set I can build that for 500.00 and discount it to 380.00
another option to consider, since you are racing them, would be adding the threaded spring pre-load option. This would allow you to set rider sag, or add spring tension to prevent bottoming. This is a 50.00 option.
Though this might give you a feel for what you can get good shocks for these days, still way under the $600 mark.
Its all just information.............. do with it what you like.