Discogs.com has a 1980 record label for "Matty Gunga Walk::
https://www.discogs.com/release/1690849-Clint-Eastwood-General-Saint-Matty-Gunga-Walk (click on the image to see it better)

It shows the song was recorded by Clint Eastwood & General Saint, backed by the Inity Rockers. The songwriters are identified as General Saint and Clint Eastwood. The label is Greensleeves, which seems to have produced a number of reggae-style or mento recordings. It is apparently a medley of reggae songs. I picked out Mary Ann and "Here We Go Loop-de-Loop," and a lot of babble.

Here's a recording of "Matty Gunga Walk" by Eastwood and Saint:
https://www.youtube.com/watch?v=5NeT5oMUvS8

I couldn't find a recording of "Gunga Walk" by the Spinners, the Detroit Spinners, or the Liverpool Spinners - but that doesn't mean they didn't record the song.

Ah, there's a page that says the (Liverpool?) Spinners recorded "Gungu Walk" on a 1966 album titled The Spinners Live Performance, also on Another LP by The Spinners (1967), "Gunga Walk" on The Spinners Vol. 1 and "Gungu Walk" on The Spinners Collection.
http://www.chanteycabin.co.uk/Spinners%20web/Spinners.htm

And here is a recording of "Gungu Walk" by the Spinners: https://www.youtube.com/watch?v=86mMlkHhpyI
I don't think the song by Clint Eastwood & General Saint is the same as "Gungu Walk" by the Spinners. Apparently, the Spinners recording attributes the song to "Trad, arr. Bosworth."

I don't think I'll try transcribing the song because a lot of it is not understandable and I have no reason to think it's authentic.