yo,
as KRAFTY advised, ask in the other section for more replies
Here is one swap to consider
300 (4.9) Swap to 460 EFI Info & pics in an 87
Source: by Nathan G (thenag, Bruiser Woods) at
http://www.supermotors.net/registry/194/13617
Nathan also gives us the electric ckt swap list
300 (4.9) to 460 Swap pics in an 85
Source: by K.C. S (The Durrdy Project) at
http://www.supermotors.net/registry/5488/19092
But, other engine size swaps to 460, or 351 can be used for the intallation such as in;
302 to 460 Swap in an 81
Source: by Ken S at
http://kenshack.net/302_to_460_engine_swap.htm
I have more in my site @
http://www.broncolinks.com/index.php?index=541
exc. for a 351C
The 460 is about 1" wider and 1" higher than a 351W; and 2.5" wider and 1" higher than a 351 C
Biut it is about 4" Longer; an electric fan helps with the extra length
your 300 weighs about 385 lbs
but the 351 C goes @ 550 lbs
351W @ 510 lbs
and the 460 @ a whOOping 720 lbs
so, spring & shock upgrades will be needed for any swap