Bongo Fury

It's an indirect injection diesel so there's no way to get into the cylinder to hold the valve in place to remove the spring

Valve oil seals stop oil getting into the cylinders.
Smoking engine is the result.
I can only assume that the bongo has this normal system.
What was wrong with the engine to need a new gasket.
Not a lot can go wrong with valve springs that you cannot see ie broken etc.
Remove the head to change the seals is the best way to do it.
You can check the valve seats and regrind at the same time.
If the engine was not smoking and you do not want to do the valves, leave the seals intact.
You can do a lot of this

Oil seals won't cause a clicking noise Kenny,
rockers will feel "loose" depending on the position of the camshaft. Have you checked the valve clearances?
The valves will hit the piston if the timing is out

You could push the valve down to release the spring with the head in place but you also risk bending the valve as they don't open directly towards the piston