Club Obi Wan

I am not to far from owning my 1st Indy jacket. I've looked into the past threads in great detail to find out what makes a great Raiders jacket. Of course just about anybody will refer you to Agent5 specs. Here's my question..
How does one know what part of those specs aren't already included on the jackets as it is? I'd hate to send a huge list to Peter. I'd like to only request what needs to be requested.
The other question is, what parts of it do I need to change the size to keep it proportionate? There's a lot of measurements and I'm confused if they are kept the same, or which ones need to be changed in size according to my jacket size.
Any help would be most appreciated. Hope I haven't over looked a thread with these questions already answered.

I would call Wested and ask Gemma to put you through to Peter to talk about leather grain and stuff. Them tell him all the Agent 5 specs and ask him which are standard. Don't leave it to an email or order form that might get lost.