Oil Pans
http://canton.carshopinc.com/p...5-600
http://canton.carshopinc.com/p...5-610
or this one if you need to cut and re-weld...
http://canton.carshopinc.com/p...-630A
transmission
The T5 is the most common transmission I believe for the 5.0, but if you can step it up to one of the newer TKOs or a T56, you can probably source a bellhousing for it easily (but probably not cheap).
If you're going the budget route, you can buy an adapter to use a mechanical slave cylinder for the T5 or you can go the hydraulic route such as the units made by Tilton and Quartermaster. (Ex: Tilton unit consists of P/N 61-601 bearing, 61-612 adapter, and 74-875U clutch master cylinder.) But, the hydraulic route is more expensive.