That JD forklift does not have a spring on the front it is a rigid non oscillating frame.

Hi, greengiant.
Forks onna dozer would have one BIGGG problem, especially if you want to slide things off them into a trailer or some such - as they lift up, they would also tilt back quite a bit, which would make it somewhat harder to slide anything heavy off of them into a trailer bed. Perhaps something like in these photos may be more helpful. Admittedly, you would have to sling each individual load but it would give better lift height and the increasing angle as it lifted would not make any difference.

www.salesandauctions.com.au/user_images/7087236.jpg

external-content.duckduckgo.com/iu/?u=ht...HaFj%26pid%3DApi&f=1

img.tradingpost.com.au/Z9V3N27C/ZT2MLY/8FWJ-Boxed640x480.jpg

Admittedly, these are all designed as tree pushers but adding a hook would make a useful crane out of any of them.

Just my 0.02.

I might have the local welding shop fabricate something. another good use for forks would be to move pallets. the last time I had to move a pallet with a pony motor strapped to it I had to drag and push it, not cool.

  deas makes a good point id forgotten about that.its the same with a simple fork frame mounted on a tractors 3 point linkage the lift in a arc not straight up and down.but a tree spear could work nicely as a lift jib with some sort of mechanical grab or you use a length of chain fitted with grab hook as a snotter(choker). to make a snotter you loop the chain around the log and then around the chain and back on itself this form a self tightening strangle hold that wont fall off easily until you want it too by letting the weight off and unhooking the hook this method has been used for decades by timber cutters to snig logs behing tractor etc i have personally used it to snig a couple of logs together and to lift posts into post holes. i have even used it on steel posts too to reposition it in concrete that was setting, the post had settled to much. yes iknow i cant draw well but you get the idea. 

I’ve seen tractors with telescopic frontal loaders that used a forklift to load and unload trucks. It was perfect for pallets, and there is nothing that you could change this tractor with.
I think you might be interested in getting one of these. I would recommend rent forklifts before buying them to see how well they work and how much you need them in your business. It is the best solution for small businesses that don’t have a system and want to figure out what they need for the most effective work. And only after renting can you proceed to buy one.