Student budget..340 or 5.9 magnum...

Hi guys as you might saw i picked up a solid 70 duster 340 4 speed , the car needs a resto but is freakin solid and planning on driving it rat rod style as is next summer , and afterwards do the body ( exterior ) like i did with my 76 duster ran on primer and cheap paint for 4 years on summer time : so heres my question money is tight for now , back to school at 32 , buying a house , got married , bought my 426 hemi last winter , cuda 70 shell and last but not least this 70 340 duster !!!!...ishhh , just want a little reliable engine , was thinking about putting the stock 340 with a little cam and headers ( needs a bit of machine work ( oversized etc ) or pull out a junkyard 5.9 for cheap but the other parts are expensive , want to put a cam in there too : SO !!! what do you think , little cheap engine for reability for this winter project , 318 360 340 5.2 5.9 ???? Ley me know and if you have recipes and budgets builds expenses etc !! Thx a lot