Hi Bearpaw..
I would make a throat impression of the rifle throat you plan on using this boolit in then I would send it to Verl so he can make a mold to fit your rifles throat..Fit is very important in regard to cast boolit shooting...Verl's site explains all this and you can buy throat slugs from him if you like...
Boolit hardness...You may find WDWW to be to hard for hunting...
I don't own a .35 Whelen but have one on order...I do have a model 600 Rem like yours...Looking at my notes I see I had best luck with 37grs of H335 (max load in Hodgdon's manual) CCI 200 primer and the RCBS 200gr (213gr.checked & lubed) OAL. 2.40" LBT lube, wheel wts. most likely WD (did'nt write that down)...Three shot groups at 100 meters ran around 1.75" with a 3 power scope...
I did this load development in 2001 with just this powder so there may be better powders...
These little 600's in that cal. are sure neat cast boolit rilfe...your post just motivated me to pull it out and take it to the range next week...
Good luck with your LBT mold and please post results with it..I will be ordering one from Verl when my Whelen gets here...
cheers,
mic