In my opinion R1a is IE, R1b learned grammar, rules etc of IE language as Mozambique people were able to learn IE portuguese language. So Basque language should be closer to oryginal R1b people. IE languages are from east, they are R1a "unwanted" sons of "Aryans" (but mothers from indo-iranian territory). Sanskrit is written in local language, not in "aryan" language. And before all of this german, english was celtic, before was (in my opinion) Basque language.
Some think that Basque language have similarity to slovenian/czech:
http://www.korenine.si/zborniki/zbornik01/pdf/jandacek_linguistic.pdf
but slavic languages are mix of indo-iranian (R1a) and I1 +I2a1b people, so the similarities can be because of older european populations here = when local R1b met I people. R1a changed our languages like french language changed Djibouti people their language.
And ones again, IE language (R1a) people is not "aryan" is a local people language which invaded and conquered R1b and I people (they came here from Egypt via near east). R1a can came here as todays seasonal worker also came. After 200 years it is possible that there will not be any Klagenfurt but polish Celowiec - if only polish people start to settle there. And belive me, even if they will be in minority they can put their rules, names etc. Bad/poor always win better/richer. This is why West gives way Russia. Poor have less to loss.