snake question..test fit and rebuilding muscle on a carcass cast

Hi!!
I followed Kerby's gaboon viper tutorial to carcass cast a snake(a ball python)..everything went well and now I have my foam form covered with bondo.
I did not sanded it yet and I am planning to add more bondo to get a good base(while sanding, i dont want go get to the foam).

My question is: after sanding and giving it a first test fit, If my form is too small, should i add more bondo and sand it back or i can rebuilt some muscle with clay or apoxy sculpt??What is the best way of adding muscle to a bondo covered form? Does any of you can share some experience about that issue?

I did not took any mesurement :-[ and i am scared to sand it witch takes a lot of elbow grease to end up with a too small form. I worked very hard on that snake , wich is my first.
Sorry form my spelling since english is not my first language.
Merci!

 

Wow Kerby himself!
Thanks for responding!

Unfortunately, I did not mesure anything but I assume that my casted body is the exact size on the snake and yesterday, after having fleshed the skin I did notice a stretch ( using a spoon ti flesh does`nt help either).

Will the skin retract to its original size after salting/pickling/tanning????

I will put more bondo to make sure that i have enuff "meat"

Thanks again Kerby..