I think you are vastly underestimating what can be done with this sort of money.
The famed Two Oceans Navy Act of 1940, the one that produced the Navy and Air Force that pounded Japan into paste that provided for the construction of 18 CV, 7 BB (2 BB-61, 5 BB-67), 6 CB, 27 CL/CA, 115 DD, 43 SS, 15,000 aircraft, conversion of 100,000 tons of civilian shipping naval auxiliaries, $50M for escort and patrol vessels (not including the DD already listed), $150M for essential equipment and facilities, $65M for munitions, and $35M for expansion of facilities? That was a total of $1.5B.
This just tossed half of that world changing Act's funding on top of the FY 1938 Budget, in addition to the 1938 Naval Act (which was the enabling act for the first three BB-61, 68K tons of cruisers, and tonnage for 8 submarines). So you are looking at 9 carriers, 4-5 BB, 3 CB (or 12-14 CA/CL/CLAA), 14 CA/CL, 55 DD, 21 SS, 7,500 aircraft, etc.
Good news for the U.S. - Full employment is coming back early.
Bad news for Tokyo - Japan is now faced with the hard fact that they only have two years to build up enough firepower to handle a massively expanded U.S., something that almost literally impossible given the relative construction rates for warships (North Carolina took 3.5 years, first steel to commission, Washington took 35 Months, South Dakota took 32, Yamato took 49 months, Musashi took 53 months; Hornet took 31 months, Essex took 20 months, Yorktown (CV-10) took 17 months, Franklin took an eye-popping 13 months first steel to commission, Shokaku took 44 months Zuikaku took 40 months). Not only is the U.S. going to build more ships they can build them anywhere from 50% to almost 300% faster, per hull. The U.S. also has four yards that can produce battleships and five that can build CV AT THE SAME TIME. The Japanese had to special build two slipways for Yamato and her sisters.