I think the winch would have driven a closed loop above the deck with the lines coming from the winch drum, through the deck via the two plastic tubes and round a pulley system on the deck. We have a Marblehead with a similar system, coincidentally also with a Nylet sailwinch. I have attached a photo below, its not as complicated as it looks. The sheets for the main sail and jib would be attached to the closed loop. I guess the aluminium tube is a telescopic main sheet post so that the sheet can be guided to a point just below the attachment to the mainsail boom. On the Marblehead in the picture this is achieved by a rather less elegant sheet metal tower/bracket assembly.
Are you thinking of planking the deck or just lining it with ink to give an impression of planking? We have done both and I would probably recommend lining as easier and lighter. I wrote an article on deck lining for the Turning Pole (the Journal of the Vintage Model Yacht Group). If you pm me your email address I could send you a copy.
I also looked at your A class on Ebay, but decided the 58 lb A class boat we already have is heavy enough to lug around. Unfortunately I cant identify your yacht, hopefully someone on here will know what it is.