The Ibrox side have been keeping tabs on the 29-year-old Spaniard as they seek a ready-made replacement should Nikica Jelavic quit the club for the Premiership.
And former Celtic keeper Javier Sanchez Broto believes the player would settle immediately into life in the SPL.
Guerra has caught the eye after impressing for Real Valladolid, who play in the Spanish Second Division, and Broto has insisted the strike ace can carry on his scoring form in Glasgow.
The hitman has netted 37 goals in 58 games for the Spanish side, a return that has alerted observers. He is a decent striker and I think he would do very well at Rangers. He is not a typical Spanish player, he is more like a British-type player," said Broto.
"He is not too big, but he is very good in the air and he is quite physical. The Second Division in Spain is still a very high standard of football, but he would be blown away by Rangers and Celtic.
"People in Spain know about the clubs. They are huge clubs and I think he would be amazed at how fanatical the supporters are.
"Javi is 29 and is an experienced player so I don't think he would have any problem settling into Scottish football. I would definitely expect him to be successful there.
"He has scored a lot of goals in the Second Division which is quite a tactical league. It is also quite defensive and if you can score goals there then you will be able to score a lot when you go to a club like Rangers because they will always create a lot of chances.
"I don't think he is going to cost a lot. The price Rangers could get him for is good value when you consider he has scored a lot of goals and will likely do the same in Scotland.
"He is at a good age to move. He still has a lot of football in him, and he knows the game."
Broto made 10 appear-ances for Celtic in 2003 when he arrived as cover for the injured Rab Douglas and Magnus Hedman.
Martin O'Neill was keen to keep the keeper at the club, only for Broto's dithering over the two-year contract that was put in front of him to mean he ended up being shown the door.
He harbours regrets over what might have been and has urged Guerra to jump at the chance of a move.
"My advice would be to make the move," he said. "Glasgow is a great city and the fans of both Celtic and Rangers love their football. The clubs are far bigger than you realise. It is only when you are a part of them that you realise that.
"He has been quoted in Spain saying he is flattered by the interest Rangers have shown in him. I think if there was a chance to make the move he would take it."
lBroto now runs his own goalkeeping academy in Spain which can be seen at www.soloporterous.com