Coal Train

I have just purchased 4 die cast K-Line K623-1012 Alaska Die Cast Hopper & K623-1131 B & M Die Cast 4-Bay Hopper (4 Road Numbers) & K623-3841 MStl. Die Cast Hopper.  What engines do you recommend (type, RR Name) to pull this heavy die cast load and what caboose would you recommend as well?  This is used on a 6  x 22 outer loop on my layout.

Frank