Alrighty I've done some work.
My computer can't come anywhere close to running the original 400x300 map (best it can do is 40000 tiles).
So first I made a smaller halfsize map. Then I decided to optimize it by cutting out Antarctica entirely

and blowing it up to 250x160, making it the largest and most accurate earth map yet.
Hawaii and Aleutians are squished in there, I know, but theyre there for gameplay's sake only. My only current quam is that the Russian mountains seem annoyingly thicker than the mountains everywhere else, including the alps.
Here is a picture, with land types, rivers, mountains, but no hills or forests:
I do intend on making the coast mimic the real continental shelf, so most areas will have a wider coast. This I will do in-game, though.
I am also adding/changing more terrains:
Ice/Barrens- mostly decorative
Snow
Tundra- one food no prod
Thinsoil Grassland (this is the coniferous line upwards)- two food one prod
Rich Grassland- three food one prod
Fertile Plains- three food one prod (may make no prod)
Arid Plains- two food one prod (may make no prod)
Wasteland (semidesert)- one food, no prod?
Desert- no food, no prod?
In river-fed areas such as the Nile, there will be four seasons:
#1 where just the underlying land is present (desert in this case)
#2 transition, with flood plains present (+2? food)
#3 flood season with floodplains present but grassland underneath alongside the river
#4 backward transition, with flood plains present but back to desert underneat
and back to #1
I still plan on immitating seasonal snowcover
And settler maps for each of the very many civs, so they know where they want to invade. I will have to write a program to do this immense task for me. Maybe using excel.
Please give me any feedback, I'm now editing this in game and would like to do any land changes asap.