Big dude myself. 6'4 and 235lb.
You'll need a wide board around the 165cm mark.
XL bindings and some boots that fit really well.
I started on a Burton King 167 camber board, 2nd hand find for 50€
Read up about board profiles, rocker, camber, everything in between.
I can't tell u what to buy, way more experienced people here for that.
I bought a jones mountain twin 164w this season, rocker camber rocker profile.
Tell the guys here what style u ride/are interested in and where u ride.