New to me 4D55

Just received new to me 1983 D-50 with 4D55 last weekend plan on dropping into the GW. Previous owner had it sitting for a few years before installing 56 head with roller rockers now it will not run.

Questions:

1. Is a D56 cam "Required" since it has roller rockers. Can I use D55 stock cam or do I have to have it reground for roller use.

2. Is the barring kit "Required" to set injection pump timing. I know it is always recommended but do I really NEED it..

3. Will spill port timing work with this motor and injection pump.

normally you want a roller cam for roller rockers, as the cam profile is easier on the wheels, slippers and jump.
not having the tool to set the timing can melt cylinders, i have heard you can go by the tone of the knock to get it close, however i have not touched timing

if he had the injection pump off (obviously) you will probably need to bleed the injection lines