^ X2
starting off with a 200G tank is fine for a little while, but ultimately you'll need a much larger tank... so i agree with PP in saying that unless you are 110% sure you can get a new and extremely large tank, then i'd hold off on the MBU and get the Lung fish...
Otherwise, if you still really want a puffer, you could consider a Fahaka, who would be more than happy to live in a 200G for life...