Several candidates so far:
-Spitfire VIII/IX, but with extra fuel behind the pilot
-early F4U plumbed for drop tanks
-P-38 as per OTL
-Mustang with Merlin XX/45/V-1650-1 and drop tanks
Also Worth considering:
-P-47 with drop tanks under wings
-Mustang X (RR conversion of Mustang I featuring a 2-stage Merlin) + drop tanks (mentioned at Sbiper's timeline)
-Typhoon with extra fuel?
How about getting the Hawker Tempest into service a little earlier?
435mph max Speed
740 mile range on internal fuel, 1,580 with drop-tanks.
The Napier engined Tempest V didn't enter operational service until April 1944. Which is a problem, however design work started in March 1940 and the prototype flew in September 1942, and it was generally optimised for under 20,000ft which is also a problem for a bomber escort.