Mirtininkas,
When I was at Regitra in October they told me that (despite the EU directive) they will not register RHD cars nor will they register LHD conversions.
You might want to check this.
When I wanted to re-register my LHD UK registered Mercedes in LT, TUVLITA would not even carry out the technical test unless I could pove it was built as a LHD car. Fortunately I had a build certificate from MB Customer Services.