Forget the name.., what's it worth to you as an hw77? Keep that figure in your head & ask yourself if the venom bit is what you want or not? My 77 cost £325 with dopia lam stock, WTC 1.5-5 2 tins of pellets & a gun bag!! Offsetting the cost of buying a stock & selling a stock + a few cheaper internal mods the gun could essentially be very similar to this rifle that your looking at for around £400-£450. (As a gun & not a venom collector!). Now I guess it's down to what you want., A nice shooting rifle or a "venom" nice shooting rifle..
I'd say if you want a "venom" nice shooting rifle then walk away unless it has the paper work to prove.. and if you want a "nice shooting rifle" then try it and walk away if it's too expensive!!
It's all down to perspective & so long as you keep close check on what part is gun & what part is name in your desires and in the cost of the gun, you should be fine