compression tester for Merc 4 cylinder

I'm faced with the very frustrating problem that my compression tester will not fit into the space available around the lowest spark plug hole on my 86 Merc. 75 HP outboard.

The bottom cowling, which apparently would have to be taken off to more easily access this cylinder (requiring me to remove the foot I think), is in the way and I need a small/short adapter to fit in the space to allow me check compression in that cylinder.

I've located the following two compression testers online and I'm wondering if it's worth paying this one guy's high shipping fees to pick up the compression tester he's offering:

https://www.maxrules.com/fixtools702.html

Another alternative would be to buy one off of amazon:

https://www.amazon.com/gp/product/B000EVU8JS/ref=pd_lpo_k2_dp_sr_3?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B00020BM28&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=1VSZCXG4CMFSXG582BHH

I like the fitting on the one the Mastertech guy is offering, but it seems a bit expensive for a compression tester. I'd love to know who makes the tester he's selling and what model he's offering, if any one knows.

Bottom line is, I need to access that cylinder. If anybody has a location solution I can go and pick up, it would be of great help to me. This must fit into the category of "a couple of tools you don't have." #-o

Take a look at these.....much cheaper and will still give you good reliable readings. Unless your a master mechanic and you want very precision reading.

https://www.harborfreight.com/catalogsearch/result/?category=&q=compression+tester

good luck !

I have a few Merc outboards & yes that bottom hole is tuff to get too.I have one that has the flex hose & you can just get in there with it.It is stilll tight with the hose,but it can be done.
I'd go with the Harbor Freight one.You just want to make sure all the cylinders are within 10% of each other.