Nobody replied to you yet?
That is a very rare machine, mate. Jennings made the first 4-reeler mechanical (the Buckaroo) in 1955, and it was such a success that Mills and Pace copied it a year later. The 4th reel made the long odds 160,000:1 allowing much bigger jackpots, typically 2000 coins or more. Aristocrat made a 4-reel version of the Arcadian, but not until 10 years later.
I wouldn't like to guess how much this is worth. The model only ran for 5 years and not many were made - a few hundred, maybe. There was a limited market and it didn't sell as well as the Jennings and Pace. Jennings Buckaroos come up on Ebay occasionally and I've seen a Pace, but not one of these. Does it have a serial number? May be engraved on the base plate. It needs a bit of work - pity about the horrible crude paint job! Many standard Hi-Top parts should fit.
Here's a picture of one with a flashy chrome case. For good measure, I attach photos of the Jennings and Pace machines. All pics from Marshall Fey's book.