xr5 timing belt slip

[xr5 fueled]

hi guys n gals, 

 

 I purchased a lv xr5, I though it was something small, but ive been told I need a new head, 

 

my question, could I take the car to get stage three mod done which replaces valves cylinders and head, 

I need to know if this would work,

 

if anyone has any ideas please dont hesitate