At the time of posting the TGY-i6 AFHDS is available for £32.32 from the UK HobbyKing warehouse. Go to the hobbyking.com website and put 9114000020-0 into the search box. Their sale may be ending soon.
The TGY-i6 AFHDS is an excellent radio and at the moment is on offer at £32.32, an almost unbelievable price for a decent 6 Chan radio. Unless you are left handed you will want a mode 2 radio which will give you steering on the right (with sprung centering) and throttle on the left (stick stays where you left it).
The Hobbyking ESC you are using has a BEC. I can see some other batteries which may be just to power the lights etc but if you are going to power the Rx from them you would be advised to remove the positive pin from the ESC connector that plugs into the Rx and of course insulate it. Alan
Your profile shows you have made one post (presumably this one). I can only assume your other posts did not appear on the forum possibly because you were indeed doing something wrong. Try posting your questions again.
I suggest you make contact with the Vintage Model Yacht Group. They have a lot of knowledge of vintage model racing yachts and regularly have meetings where they sail restored boats. Here is a link to there website:- http://www.vmyg.org.uk/ Alan
If you want to get performance similar to the Merco using electric power you will have to go brushless. We have done this successfully with the 46" Crash Tender and the details are on this website:- To see the boat In both static and action pictures (well up on the plane) go to the Photo Gallery and select Fire Boats. Go to the entry by mrpthesailor dated 13/11/08 on page 2. To check out the power set up go to Your Power Setup section and scroll down to the entry by mrpthesailor dated 13/11/2008. Here Is a link to the power setup:- http://modelfireboats.com/rc/setups.php A power setup like this does not come cheaply but the results can be Impressive. Duration will depend om how you sail the boat, with realistic cruising mixed with high speed runs should give about 15 mins.