I have the 305 V-6 also and YES will will need to remove the water bridge to replace the hose. The hose size is standard and most FLAPS have it. You can make the gaskets from the off the shelf material. (Trace copies).
On the valve adjustment, Do you have the factory setting or do you need them? I adjusted mine first cold, then warmed her up and rechecked them. All you need is a GOOD closed end wrench, THEY will be hard to turn, use at least an 10-12" GOOD quality wrench, NOT "Harbor Freight quality stuff".
Do you have a shop manual? IF not I can copy the needed pages for tune up, but the book will also tell you all sorts of needed stiff.
Here is one on ebay. THIS IS CHEAP TOO, I had to pay 50.00 when I found mine. The years differance will not be any problems for the engine just the body style.
