Before spending much time and effort on the capture side, you should investigate how much it's going to cost to print & mount these images. For this, look to commercial labs and fine art printers in your area. Chat with them as to what you'll need in an image. Gallery quality at that size will be over $1,000 so if you're doing a series of these, know what your costs are up front.
Based on what your printing costs will be, you'd be happier with the results using a full frame camera and quality lenses. Expect to spend $3-5k on this.
Your subject matter leaves this thread very questionable, but to each their own. Generally speaking, start with the camera you purchased, learn and stick to smaller print sizes for now. Making a print bigger doesn't make it better.