Opinion on Masaki Promos?

Thoughts on Masaki promos long term? I picked this Gengar up for $900 and the Alakazam PSA 8 for $320. Is it worth completing the whole set of Masaki's to sell for a premium down the road? Or better to put that towards other vintage chases? I'm also debating other vintage Gengars. Just for a small slab collection, I understand sealed > slabs