All Day Shirt sizing help

Hello! I am wanting to make the All Day shirt for someone as a surprise. I don't have measurements, but I measured one of his shirts. The measurements were chest: 43", waist: 37", Length: 27.5", Collar 17". I was thinking a medium, but a large looks like possibly a better fit. Advice for me? Looking at finished measurements, I could do a medium and his shirts in RTW are Mediums, but the collar measurement would be too small. Thanks!