Fixed bucket seat for tall/wide people

Hey guys, based in the UK. Purchasing a GT Prime at the end of April, noticed the seat options for the fixed Chase and Inertia are basically child sizes.

Now I'm 6'4 and around 15-16 stone with a 36 inch waist, looked at the Sparco Evo XL and I don't REALLY want to break the bank with such an expensive seat. Unfortunately there is nowhere close where I can go and try seats before a purchase so I realise I'm going into this a little blind.

Found these https://www.corbeau-seats.com/product-page/pro-sport

https://bbclassics.co.uk/products/bb5-extra-large-lightweight-fibreglass-fixed-bucket-seat-sidemounts-runners?variant=44719941124398&country=GB&currency=GBP&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&cmp_id=19179379818&adg_id=&kwd=&device=m&gad_source=1&gclid=EAIaIQobChMI2P7UtqqniwMVLodQBh3wxD1jEAQYCSABEgIi4_D_BwE

Not sure if these would be just as viable in regards to a snug but comfy fit along with being tall enough from butt to top of my head so my head isn't milee above the top of the seat.

Any insight or info would be massively appreciated!