Nick - here are a few references on the varying Martlet models. you would want to build the Martlet Mk I, specifically called out on one of the provided websites as having only the upper carburator intake scoop (you'll have to sand or cut out the inner cowl scoops) and no cowl flaps. Just putty them up a bit above the level of the plastic and sand it down to get rid of the ones on the kit. It seems all the other variations for that particular model were internal so you wouldn't see them.
http://www.vectorsite.net/avwcat.html (pay attention to the mention of the French order of Wildcats about 1/3 down the page. These were the Martlets flown in the BoB. to qoute:
"The French variant was the Grumman "G-36A", to be fitted with the Wright R-1820-G205A Cyclone 9-cylinder single-row radial engine with 750 kW (1,000 HP) and driving an uncuffed Hamilton Standard propeller. It was fitted with a shortened cowling, with an inlet in the upper lip but no flaps in the rear. The G-36A was to have fixed wings and six 7.5 millimeter Darne machine guns, with two in the nose cowling and two in each wings. The guns and other French kit such as radio and gunsight, were to be installed after delivery. The French ordered 81 plus 10 complete sets of spares."
The intake on the F4F-4 kit is a little too high but it will work good enough to give the representation of the Mk.I Also I *believe* the Brits only put the guns in the wing on these particular aircraft.. so two guns per wing. You can sand and putty the third one off.
http://fleetairarmsig.netfirms.com/articles/martlet/scottspencer-martlet/martlet.html
http://www.clubhyper.com/reference/martlettipe_1.htm (I wish I had found these pics when I did my BoB Martlet way back when, a lot different than the decal call out sheet, especially the demarcation line.)
If you want to be very realistic, here's the rough pattern you will need to cut out of the floor of the cockpit. If it is the Tamiya kit there are definite markers you can use to go by to cut it out. Namely a raised center stripe, just cut towards that and that will be the center post for the seat. The cutouts were to allow the pilot to see through the lower windows in the belly.
I've got some more references so if you run into a snag let me know.. I'll see what I can dig up for ya!!
-=edit=- sorry... my exhuberance over another Martlet being built got the best of me... I built my first one up almost OOB, only puttying the flaps and rescribing a single line to represent two large flaps as I was reading about the BRITISH Martlets not the French order... feel free to have fun and just build OOB if ya want! It's a very enjoyable kit and didn't want to give the impression I was a rivet counter... I just love the aircraft! It was the first US built aircraft to down an Axis plane... almost a yr before we entered the war! (A FAA Martlet downed a Ju88 over Scapa Flow) Enjoy!!!!