Hi Matt,
Good to see someone tackling a Lima 33. There are some really good tips that I have picked up by either talking to or studying the work of other diesel modellers. Dave Furmage, James Wells and Pete Johnson and others have proved to be been great influences on the methods I use to detail my Diesel Locos and take all the credit for the tips below.
Markits do an extremely nice blackened turned brass unsprung Oleo loco buffer, I've upgraded my Heljan 26's, 27s and Bachmann 20s and they are a major improvement on the ones originally fitted. Check out the Markits online catalogue, you need to look for part MBUFOLEO on page 18. They also do a sprung version of this buffer which I am yet to try out. Also, if you are looking for other bits such as pipes and jumpers to upgrade your Lima 33, check out the Heljan spares stocked by Howes. They have various sprues available for no more than a few quid each and again are an alternative to making your own. Hornby Buffer Beam detailing packs are also excellent if you can get hold of them. James is right about using 10 thou rod for window surrounds, it's not too difficult to do if you take your time, and you can make a really big difference to your models if you Flush Glaze them using Evergreen 15 thou plastic sheet cut and filed to size. I buy all my plastic sheet and rod from Hobby Holidays. Finish all of the aforementioned with Wire Handrails (I use Alan Gibson .45mm Brass Wire sourced via Mainly Trains), Etched Lamp Irons (bent into shape using Mainly Trains 75 thou Brass Boiler Banding), Etched Wipers (Shawplan) and where relevant other etched details from the Extreme Etchings range produced by Shawplan. I have no interest in any of these suppliers except for being a very happy customer, though I will confess to being friends with Brian Hanson of Shawplan who is also a member of the DEfine Group to which I belong.
I hope the above is of help.
Cheers
Chris Messer