Mopar Performance Aluminum Rocker Arms

I don't really have a whole lot of knowledge on rocker arms...Would these work on a stock 318?
Yes

-will I need custom length pushrods?
Probably, but that is an easy thing to take care of.

-what hold downs and bolts do I use to mount these rocker arms?
Stock ones work fine, MoPar has a really nice set and Huges engines has a geourous (SP?) set.

and where to get them?

MoPars can be had at the dealers, Huges at there on-line shop; http://www.hughesengines.com/Index/index.php

would the stock bolts and spacers work?
The rocker arms should come with the spacers, bolts for the hold downs should come with the hold downs.

Scamp408's deal is very good even if he doesn't have the spacers, they can be purchased seperatley at a low cost from many places as well.