We discussed this a couple or so weeks ago. If you mean USMC suitable for 1965/66 in OG 107 temperate uniforms, M-1955 flak jackets, M-1961 webbing and M-14s then the short answer is no.
However, you could modify the Rubicon USMC with a modicum of effort. You would need to cut/file off the cargo pockets on the trousers and you would need to supply your own M-14s but plastic is the easiest medium to convert and I've converted a few of the Rubicon US Army and PAVN plastics myself, in fact it's been my main use for them. The Rubicon USMC box comes with the M-1961 webbing, so it's the best start point. TAG produce M-14s as stand alone weapons:
https://theassaultgroup.co.uk/product/m14-rifle-x-10/If you can't be bothered converting then your next nearest proxies would be the TAG US Army with M-14 figures. They are in tropical uniforms, no flak jackets and have US Army issued M-1956 webbing, which wasn't really a thing with the marines until later in the war but attention to detail is a moveable feast. the TAG Vietnam range are fairly big, beefy buggers. They won't mix well with Empress or Rubicon, probably a better, fit with Gringo height wise.
One day, someone will hopefully fill the gap and produce some marines suitable for Starlite/Satellite and the Dominican Republic. Fingers crossed.