Head gasket

Just got head back from skimming they removed 4 thousand from surface
Need advise on what size head gasket to get and how to measure cheers or do I just get same cheers

What you have in it before !
Some things you will need review for HG thickness are what block & head skimming been done in total if this not the first skim.
what compression ratio you plan for your build
what pistons & cams you got ( have you got appropriate clearance)
what gasket manufacturer you buying from as they differ in available size range

if previous gasket was well chosen then a skim of 4tho which like 10th of a mill is no major change.
If unsure of what work been done before then it wise measuring block & head to see what been taken off it (workshop manual has data on this)

Got forged Pistons in not sure of make old head gasket is
88m bore and 1.7mm thick not sure on compression just want something reliable old gasket as number 2 above each piston

what your piston/bore size ?
cosworth do 87mm bore & 1.8 which likely what you had, 1.8 is bit thick though unless had lots of machining done or require the low comp ratio for your build agenda.
ideally you want measure block & head depths so you know what been taken off before as it possible a 1.5 gasket could be best choice.
also match head gasket to block bore, is tricky with cosworth as they only do 87 & 90 bores, I tend use apexi gaskets fair bit as their 1.5 87bore & 88bore tends lend itself well to many rebuilds

How do I measure block and head carnt find it on here

PDF file is in useful links section

direct link below for relevant PDF
https://drive.google.com/file/d/0B7Ub2apq5-pfQXVvdXNRb3ZRanM/view?usp=sharing

Cheers

Still confused with which head gasket to get old head gasket bore is 88mm but engine bore is 86.5mm do I get 88mm bore or 86.5mm bore sorry for all the post

I'd say if you're going for mild boost upgrade get 87mm bore 1.5mm thick cosworth gasket but everything depends on what you're planning to do with car... I don't know if you can actually get 86.5mm bore head gasket