Diesel Bombers - Help needed, Newbie wanting to learn.

I do want to apologise ahead of time long post with poor grammar, first time on a forum.

So I just bought a 1998 12v 1 ton. The privious owner built it a little too much in my opinion. Its a 1998 3500 12v 5 speed 1 ton 4x4, .20 over, 90over injectors, rebuilt bottom end, built top end, twin turbo (44mm/68mm), fueled by a airdog 165. Theres alot more done to it feel free to ask about it. I got a good deal on it but i bought it knowing it needed some love. The issue was when it peaks boost it would blow coolant out the radiator cap. Did some research and it could be a numer of thing but narrowed it down to 4 things 1.cracked head, 2. Cracked fire ring, 3. Head gasket or 4. A lifting head, so ive currently got the head ready to come off. But working in the dirt so im waiting for good weather before i open her up. On a side note the smaller turbo seal is really bad oil everywhere, currently fighting with the intercooler to flush the oil out. The issue here is my turbo doesnt have the holset stamp on the housing so i cant find what rebuild kit i need. Ive tried contacting holset and they couldnt help, Any help there would be great.

Another issue is all the piping is custom made, poorly made if you ask me. The air intake in a awful spot. Has anyone seen or heard of batteries mounted in a toolbox with the old grille mounted jumper conectors, Or any other way of reloacting the battery to fit a better air filter?

Theres alot more ive been doing on the side with it if anyone knows and is willing to help im all ears. But im looking to do things the right way but im all up for fabrication if needed but not duck tape and super glue.