It will be a pain to do with the low poly models in SH3.
The basic steps would be:
create an object the shape of the holes,
place that object where you want the hole,
do a boolean cut,
repeat for every hole.
You'll then need to do other work to avoid the see through issue.
A quick way to get the 7b, 7c, 7c41, is to take the models from SH5.
SH4 will have the 9d2 model.
It's alot of work no matter the course you take.