Many things for the mr2 are discontinued (meaning need to find second hand) or an out dated design and better components available.
Due to demand by the mr2 community there are many upgrade parts available. The filler neck, as example, (quick grab from google)
https://www.tcsmotorsport...motorsports-water-neck I believe they do one that deletes the part you are looking for, reduces failure points, looks bling, and will set you back about $300+ aussie delivered,