dude, do what i do, get a rear rim on the front, and a rear tyre with dh tube on the front.
pashley/curtis forks, threaded 1/2 inch bar as a headlock
take crank bolts out, repeat again, threaded bar
gusset tank chain
old school sun doublewide rim
heavy is good to an extent, the fealing of less flex at durability is far more confidence inspiring then weight watching, seriously though if your doing it for training purposes, just look into your power to weight ratio..
i find gym helps alot, and i dont go to train for trials, i go to look better, at 16 stone now and i gotta admit bikes are starting to feal very flexy
the front rim is deff a good idea though, mpore stability on front end