Oh, where to start here....
Originally Posted by MasterMagician
I've been out of racing for almost 12 seasons now, and am used to extremely stiff 70's vintage DH boards at (I think) 217cm.
So what are my options for straightest and stiffest modern DH boards? Also, where might I buy some gates? I plan to train on old class A trails like the Thunderbolt on Mount Greylock, because it's usually empty and extremely technical, and also perhaps a bit at Sugarloaf where they actually tolerate civilians skiing at 80+ mph, but not on Narrow Gauge because obviously CVA has that baby locked down when the snow is fast enough. So I'll need my own gates, drill, flags, etc...
First things first: a "straight and stiff" DH rig won't work well in most modern DH courses, which are set with far more turns than used to be the case. As mentioned earlier, you can find good, modern DH and SG boards on eBay, as well as from online race-oriented shops like Edgewise (they have consignment skis for sale in great shape, and all are tuned by Graham Lonetto, a former World Cup ski tech).
That said, your training plan sounds like a disaster waiting to happen.
First of all, there's no way that any ski resort would let you set gates on a trail for any kind of training. Academies, resort teams, high school and college teams and clubs all work closely with resort management to work out issues of trail use, liability and safety. The teams set on pre-approved trails and take appropriate safety measures. If you tried to to this on your own, without working with the resort on safety considerations, you'll likely find yourself kicked off the mountain (sometimes for good, if things go down in a negative way).
This goes doubly (if not far more than that) for training speed events, where safety nets are often required and large swaths of mountain closed to the public. Most speed training takes place during off-hours at resorts, typically early morning, prior to the public having lift access. This allows the teams (and the resorts) to setup courses with proper conditions, safety fencing and nets, and the minimum chance of the public skiing onto a course (lemme tell 'ya, you never, ever want to hit another skier going at DH or SG speeds - it's nasty for all involved). Otherwise, sure, the racers will freeski on DH or SG boards, but not at full speed - and ski patrol is keenly aware of the racers who train at their resort and are most adept at pulling passes for those who push the limits (and yes, Sugarloaf is well aware, too).
As far as the Thunderbolt trail goes, good luck getting the Massachusetts State Parks officials to smile upon folks setting up gates and such on the trail without a permit - ain't gonna happen. They're all too aware of the liability involved, and any races that take place on the T'bolt are approved well ahead of time.
As MojoMan suggested, your best bet is to attend a speed camp and some of the speed races organized by New England Masters Ski Racing. They tend to have short camps before their speed events, take all the necessary precautions, and put on top-notch events. also worth looking into is the series run as the North American Downhill Series (or N.A.D.S.). This is a series of non-USSA speed events in New England, the most famous being the George Syrovatka DH at Jay Peak in March.
So hook up with a local masters racing club and see what can be done. Going it on your own, tempting as it may seem, is asking for trouble on many fronts.
Just my $0.02 as another DH racer from years past.