Thanks everyone for all the help, just an update, I've now transferred the 800k into my Krungsri account. 2 x Wise transfers from UK that happened in seconds, not minutes and not hours ... So all good, i now wait for the IMO appointment in. 2+ Months.
Not sure why this conversation got side tracked into US tax requirements, but that's normal i guess on these platforms..
I'll update as i continue through the process...
Thanks
W