Problem with player model rigging

So I offered in an earlier thread to pay around $40 for this player model to be made, but no one seemed interested. So I decided to try and make the player model myself, I know nothing about Modelling so I had to follow a tutorial to make this, but the tutorial only taught you how to make models with similar proportions to the valve biped into a player model, but the model I’m using has longer arms than the valve biped. I actually scaled the biped to my model but when I exported it with wallworm ( I have 3DS Max 2016 by the way) it scaled the biped back to it’s original proportions which really messed with the rigging on the arms. So what I was wandering is if someone would be willing to fix this issue for me, I will send you the files if you decide to (if you do I’ll add you as creator when I upload it to the workshop). Or if someone would be willing to guide me through fixing this that would be very helpful as well and I would still give you credit on the workshop page. I know someone is going to say it’s not rigged correctly but the arms were in the correct position before exporting with wallworm. Here’s a picture of the issue >>>>

Add me on Steam and I will fix it for you.